The nihilism comes in when (it is perceived that) it doesn't matter that even if you do the right things (get educated, learn a skill/trade, work hard, don't spend too much), things are in such a state that that won't help, so why not YOLO?
Rent eats up half your take home pay and while you're not terrible with money, you are also not super frugal. So you are ultimately saving a few thousand a year. At this point road to being rich is half a century away and pretty narrow. You better not get sick, or have to take care of an injured family member, or scammed, or divorced, or laid off for an extended period of time. And all around you is a media, political, and social ecosystem telling you the good times are over.
It makes sense why some people just decide to lie-flat.