system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: Pessimism is no more "realistic" than optimism.

I hear pessimistic people make the claim that: "I'm not a pessimist, I'm a realist." When pushed for more information, they usually make the claim that their worldview is somehow more accurate than that of an optimist. 

I disagree. I feel that you create your own reality. If I spend my days practicing gratitude and putting out happiness and optimism, my life will be better. If I focus on all the things that go wrong with the world (the news), see challenges as threats rather than learning/growth opportunities and treat everyone around me with bitterness, of course life will suck. 

Pessimistic people are no more realistic than optimistic people. 

Change my view.

Edit 1: There are some great responses here, some are very close to a delta. I will respond to each within the next day, I just got a lot busier than expected.
gpt
Have you heard of the planning fallacy?

It's is a phenomenon in which predictions about how much time will be needed to complete a future task display an optimistic bias (underestimate the time needed).  It's also the tendency to underestimate the time, costs, and risks of future actions and at the same time overestimate the benefits of the same actions. 

In a 1994 study, 37 psychology students were asked to estimate how long it would take to finish their senior theses. The average estimate was 33.9 days. They also estimated how long it would take "if everything went as well as it possibly could" (averaging 27.4 days) and "if everything went as poorly as it possibly could" (averaging 48.6 days). The average actual completion time was 55.5 days, with only about 30% of the students completing their thesis in the amount of time they predicted.

70% of people underestimate their requirements even when planning for a worst case scenario! If this was something more serious, like a job deadline, they could cost the company a lot of money, or lose their job. If they are a military strategist, it could lose a battle!

The 30% of students who completed their thesis in the time they predicted, would have been called pessimists by the rest of the class. They would [ quite rightly] call themselves realists.

A "pessimist" would pack plenty of food, safety gear and first aid equipment for a week long hike "just in case" an optimist wouldn't even pack enough stuff for a best case scenario, and so when someone inevitably gets hurt, they end up dead.

Optimist's also make poor choices because they under estimate risks and overestimate benefits of actions they take.