It is nice when OPs are honest, and don't keep changing the goal posts and reasons for threads.
If you want to understand spending better, then dig into the research on different spending and savings patterns by age - there are entire websites dedicated to that type of information. All people here can give you is personal experiences and links. If you want to know more about how people trust young people with money, then ask that. If you want to rant at us about having a different view of money, well, you've done that.
Not everyone who doesn't have 20k at 20 is 'terrible with money' because of a 'preference to waste their money at a young age'. If you want to dismiss a 'majority of young people' in that regard, that's up to you, but it's rather thinking the worst of people -- and I don't get asking a forum full of people of all ages about this.
Saying many can't do something isn't saying it's impossible for everyone. It's simply acknowledging the reality that many people can't just work those hours and constantly save as they have expenses required to continue existing. All the money I made as while in school, I used to eat and go to school, sometimes I had to do without the former to do the latter -- and that's while a parent was providing a roof over my head which yes, is parental support. Ignoring that is ridiculous, even when considering situations like mine where living away from parents with others was more financially stable for me than living with either of them.
Yes, I then made really expensive choices, but I don't consider immigrating or having kids a waste. Risky choices, certainly, but that's life, which is what I use money for and now significantly older than that, I'm financially comfortable even with a risky start.
I personally would not view what you said as 'the best life' as I have never desired to spent a lot of money in a club or on designer clothes or cars. It's not jealousy, I achieved the goals I had at that age - happily married, immigrated half way around the world, and quite content. Not everyone is financially driven, that doesn't make people 'wrong', just different.