I wonder how many of them are actually happy?
I know a few, and they are no less happy than most people, like most people they kind of want a better life, but they are enjoying the freedom their choice gives them. Some of them if they want a few extra bucks, they chop wood to sell, or help clean lots, or clean fish. But mostly they just enjoy the life, they can go pick berries when they want, they can fish and hunt when they want. They are a lot like retired people, happy with where they are and free to do when they want.
There are people who do that in Australia and surf out the back of a van. There is one important difference with retired people though - a retired person has lived a life and got to that point, a younger person might not realize there are things that they might want later in life - but they no longer have the path to get there.