(CNN) -- They didn't have to die.

This is the terrible truth of America's new pandemic battlefront, as the malicious, highly infectious Delta variant surges, targeting millions who sadly left it too late to protect themselves with safe, free and effective vaccines.

Michael Freedy, a Las Vegas father of five, could still be the light of his kids' lives. Instead, they will be always haunted by one of his wrenching final texts before he died on Thursday: "I should have gotten the damn vaccine."

Kim Maginn, a 63-year-old Arkansas grandma and fitness enthusiast, should still have years to watch her family grow. Instead, her daughter, Rachel Rosser, a nurse, is left to ask why she couldn't convince her late mom to get her shots.

"I'm angry that she didn't get vaccinated. And I personally feel guilty that I didn't try harder," Rosser said.

Unfortunately, Maginn had reasoned that if she was going to come down with Covid she would have gotten it by now.

The loved ones of the dead are not alone in their poignant laments.

Some of those who survived a bout with Covid -- after long days struggling for breath or saddled with debilitating side-effects -- wonder why they didn't take a simple step to spare themselves and their loved ones from the nightmare.

Ganeene Starling, a Floridian who has eight kids, shivered to think what would have happened to her 6-year-old had Starling not made it through what she said was a "horrifying" spell in the intensive care unit. She admitted listening to people who said the government was forcing people to fill their bodies with an untested substance.

"I was one of those people that was like, 'I can't believe people are just going to just inject their body with this medication that we don't know enough about,' " Starling, 43, said. "Now I'm like, 'It's just a shot. Just get the stupid shot.' "

"That vaccine could have stopped all of this. Just one little shot. I feel foolish that I didn't get it."

As Alicia Ball sat by her husband William's bedside, where he slumbered in an exhausted sleep in an oxygen mask last week, she said they had delayed getting their shots. But she told CNN from Mississippi: "I wouldn't want my worst enemy to go through this."

A vast tragedy

As infections grow, powered by the Delta variant of Covid-19, these devastating stories of needless human loss and pain shared in recent days with CNN anchors and reporters -- including John Berman, Martin Savidge, Randi Kaye, Miguel Marquez, Chris Cuomo and others -- will be repeated thousands of times over. Some of those offering testimony agreed to speak out even while mourning and experiencing personal agony, to help others avoid their fate.

The vast human tragedy of the pandemic -- with more than 600,000 American deaths alone -- was already almost unbearable. But many of those lost in earlier waves of disease didn't have a chance.

Some succumbed to comorbidities that left them vulnerable to Covid-19 -- an illness for which there are few effective therapies. Others got sick after not taking the disease -- and the social distancing advice of government scientists -- seriously enough. Many were just unlucky and condemned to their fate by biology or chance.

But the idea that many such tragedies can now be avoided -- but won't be because, for whatever reason, millions of American adults won't get vaccinated -- may herald the most painful phase yet of this cursed global emergency.

Most people who get Covid-19 will still not die or get seriously sick, a factor that has clearly colored the calculations of many in the country who are suspicious of public health advice or think the worst won't happen to them.

But the latest data from the US Centers for Disease Control and Prevention, combined with the vicious march of the Delta variant, weights the calculation even further towards getting vaccinated before it is too late.

For all the talk of "breakthrough infections," only a tiny proportion of those who are inoculated against Covid-19 actually contract the virus. A smaller number get sick and need to go to the hospital. An even tinier number die. So, getting the shots, while not offering a 100% guarantee of survivability -- the fragility of human life mitigates against that -- offers enormous and stunning protection.

The CDC said on Saturday for example that less than 0.004% of people who have been fully vaccinated against Covid-19 experience a breakthrough case resulting in hospitalization. Less than 0.001% died from the disease. While the tally of those breakthrough cases -- 6,587 -- and deaths -- 1,263 -- seems like a lot, they need to be set against the fact that more than 163 million people in the United States were fully vaccinated against Covid-19 as of July 26.

And the CDC reported on Monday that 70% of all US adults have received at least one Covid-19 vaccine shot, reaching a benchmark goal that President Joe Biden had hoped to hit a little less than one month ago.

Reasons for vaccine reluctance

Given the staggering success of vaccines, even as the Delta variant lays siege to the country, the decision of many Americans to forgo the protection that could save their lives comes across as puzzling to those who have their shots.

There are many reasons why people are reluctant. Some wanted to wait and see whether there were any side effects over time for the vaccinated. Suspicion of government runs deep in the American soul, undermining some of the Biden White House's pleas for people to go ahead and protect themselves.

In some parts of the country, left largely untouched by earlier Covid assaults that emptied the streets in great cities, there was a feeling that the disease didn't pose a serious threat. And since most people get better from their infections, there is a strong sense that your chances are still pretty good if you do get sick -- especially if you are young and don't have preexisting health conditions.

In many cases, the pressure of work and busy lives causes some people to put off their shots. Politics also undeniably played a role. The fact that ex-President Donald Trump, despite presiding over an administration that helped fund the development of vaccines, politicized Covid-19 so grievously and mocked mask wearing means it can hardly be a coincidence that almost all the least vaccinated states voted for him last November and are now badly exposed to the Delta variant.

Months of anti-vaccine propaganda by conservative news networks watched by Trump supporters stigmatized the vaccine for many. In Missouri, which is being hammered by Delta, CNN reported that some people are getting their shots in secret to avoid social and political pressure to hold out.

"They didn't want to have to deal with the peer pressure or the outbursts from other people about them ... 'giving in to everything,' " Dr Priscilla Frase, an internist and chief medical information Officer at Ozarks Healthcare in West Plains, told CNN's Anderson Cooper.

Even now, many Republicans appear to be making a political decision to avoid the vaccine despite its life-saving potential. A Monmouth University poll published on Monday found that 17% remain opposed to getting the vaccine at all. Among that group, 70% either identify with or lean toward the Republican Party, while just 6% align with the Democrats.

The idea that anyone would not save themselves because they are listening to a politician (not just Trump) who is downplaying the pandemic to boost their own career, or a right-wing pundit spiking their ratings, is its own tragedy.

But no matter the reason, it's increasingly clear that people who refuse the vaccine are now taking a significant risk with their own lives and health -- and the well-being of those who might be left behind if they die. With kids under 12 still ineligible to be vaccinated, the skeptics also risk exposing the youngest and vulnerable members of society to a serious disease. Ultimately, they are laying a wager in what West Virginia's Republican Gov. Jim Justice called "a death lottery."

'It's not worth it'

The controversy over vaccines has once again exposed the deep political and societal chasm cleaving the United States. And it raises the question of whether getting vaccinated is not just a personal choice but a step that should be considered in terms of an individual's debt to society.

This question is especially difficult for many doctors and nurses, who have spent more than a year surrounded by Covid deaths in ICUs. Many share stories of people refusing to believe that they have Covid-19 even up until the moment they are intubated. Others beg for the vaccine -- even though once you get sick it's too late.

"Some people insist that we're lying to them about their Covid positive diagnosis, even sick people," nurse Morgan Babin told CNN last week in Louisiana where the virus is rampant.

The reality of unnecessary death is adding to stress and damaging morale among many medical professionals as the nation gears up for another prolonged battle against the virus.

"It's also very frustrating. We're human, too. As physicians, nurses, respiratory therapists, etc., we have basically a miracle drug," Dr. Murtaza Akhter, an emergency physician at Florida International University, told CNN's Ana Cabrera last week. "We have something that can help prevent infection and especially completely prevent severe infection and yet people refuse to get it. And they come in begging for help but also refusing the vaccine."

"It's utterly ironic. It's very, quite frankly, anger-inducing."

One patient who learned that lesson was Aimee Matzen, 44, who told CNN in a hospital last week that she was "furious" with herself because she was not vaccinated.

"(I) just don't want anyone else winding up like me, especially when the vaccine is so easy to get now," she said.

Michael Freedy's fiancé Jessica DuPreez -- who got her shots as soon as he tested positive -- told CNN's Berman on Monday that she believes that he would still be with her if he got vaccinated.

"I do, I think that it at least would have lessened the symptoms and he could have fought longer and had a better chance," she said. DuPreez said the loss of Freedy, 39, still feels surreal. His 7-year-old son still sends texts to his phone. "The very first one was Dad, are you still alive?" she said on "New Day."

"Those of you that are hesitating and think 'it can't happen to me because I am young' -- it can and then you're going to be sitting there wondering why you didn't and you're not going to be able to hug your family again."

"It's not worth it."