It's not that easy to disconnect yourself from humanity as you make it up to be. Covering your running costs without a steady job is hard and takes planning. Also I don't believe you can get a "house" for 20k anywhere. Maybe a cabin in a forest with no electricity and running water but that doesn't count.

That said, there are tons of people living like that. And claim to be happy with their lives. So either they are lying or your assertion that "everybody works like this" is wrong and some people just doesn't want to be around other people.