Rent is kind of bullshit. I mean, it's not bullshit in theory, that you might fancy someone's property and pay them for the privilege of using it. But when this property is basically just walls and a floor and a ceiling (albeit with a few nifty appliances thrown in), it's bullshit that it should cost so much to sit inside it.
And it's certainly bullshit that anyone would pay for this without even stopping to consider if it's actually worth it to them.
There might be circumstances in your life that require a conventional living arrangement. Maybe you're 97 years old or nursing a newborn baby or recovering from some sort of injury. Do what you need to do. But if you're young and healthy and don't have much baggage in your life, you probably don't need to pay for rent.
All you need is a safe place to sleep at night. To get this, you need to be warm, on a level surface, preferably have some sort of padding under you, and have relative peace and quiet. There are certain requirements. But you don't need walls around you and an official postal address associated with your location.
Whether you camp deep in the forest or roll off near the side of the road, or whether you stick to one location or travel around aimlessly, you're only limited by what you're able to discover. You can basically camp anywhere you want as long as nobody sees you. And when you realize you can actually do that (at least in my experience), the illusion that you should pay a bunch of money for rent quickly evaporates. (And then all the people who are immobile or otherwise needing a conventional residence are helped out by the deflating demand and dwindling cost.)
You might give up some perks by not having an apartment, but for me, sleeping isn't really one of them. In many ways I prefer sleeping outdoors. An air mattress and a couple blankets is plenty comfortable for me, and there's really no way to beat the open air under the stars.
I like the personal space of having an apartment, but I don't really require it to perform the basic functions of being human, so at hundreds of dollars per month it doesn't seem worth it to me. At least not routinely. I can buy a hotel room or find something short-term if I really need a place to lounge around and jerk off for a while.
Other than that, everything about the rent free lifestyle is ideal to me. It's trippy, and I guess liberating, to wake up and realize you can move literally wherever you want today. If you feel like riding your bike across the Golden Gate Bridge, you can go to San Fransisco, and stay as long as you'd like.
Is it safe? Sure. I mean, I guess. There are risks with everything. Could a mountain lion attack me while I'm camping? I guess, sure, but a gas tank could explode while I'm sleeping in a house. Altogether I don't think the risks are really any different than the general risks of being alive. The worst case scenarios are more unconventional, but that doesn't mean they're actually more likely.
Depending how much money you want to spend, you can function fairly normally. You can get a gym membership so you have a place to shower. You can get a UPS box so you have a place to get mail. You can rent a storage unit if you have "stuff" to look after, or even just a lot of clothes that you don't want to cache in the woods. I highly recommend carrying a laptop around with you, but paying for internet service is optional with wifi hotspots being just about everywhere. You should be able to live very comfortably for $100-200/month (before food), which isn't free, but it's a lot less than rent. And of course, you can range that down towards $0 if you don't mind smelling questionable, foregoing snail-mail, ditching your stuff, etc.
I definitely don't advocate this lifestyle in particular to anyone. I barely know what's best for me, let alone what's best for you. But I know for sure it's possible. And I know rent is kind of high in an economy that's kind of terrible, so I think a lot of people would be better off this way. I find it to be less grinding and way more in tune with my natural rhythms.