system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do extremely mentally ill homeless people survive?

I'm curious about how homeless people who are completely obviously unhinged survive day-to-day life. I mean the people that can't even speak or hold a conversation beyond yelling gibberish at random passerby. How does somebody seemingly incapable of even begging for change find food and water for themselves? I honestly have no idea since I have no experience with them beyond random encounters in the street.
gpt
Don't need good social skills to dig through a dumpster for discarded food or clothing.

There are also soup kitchens that might feed them as long as they behave while on the premises, even if they might still say unusual things.

They might have good and bad days too, like most people. Perhaps they're able to keep it together for long enough to buy some bread one day, even if they were behaving erraticly some days earlier.

In some areas, there are cash refunds for empty cans and bottles. Homeless people in these areas often go around collecting these, and turn them in for money. You only need to find like 15 bottles to be able to afford a loaf of bread, which might sustain you for a few days. Sure, it's not a varied diet, but it keeps you not-dead, and you can supplement it with random stuff you find (or steal) elsewhere, like the occasional fruit, or maybe even some meat if you're lucky.

As for water, you'd be amazed at what you'll drink if you're thirsty enough, and cities often have fountains or other running water somewhere. Maybe they'll find a half-empty water bottle on the ground now and then too. They might keep a bottle to fill up whenever they come across fresh water.

Eating and drinking random stuff you find lying around is of course risky. It could be contaminated with lots of stuff. That's why it's not exactly uncommon for homeless people to be of poor health.