I would say your particular case is the exception, not the rule. If I look at my graduating class, there's a pretty clear trend where people who screwed around and did drugs in their 20s are still generally screwing around and doing drugs - and quite often pretty unhappy (and sadly a few close friends have passed away from overdose). And people who hustled after graduation are much more likely to be married, own a home, have kids, etc. To be clear - I'm NOT saying that having a home, a family, or money are either necessary or sufficient to be happy, but in general I view it as a pretty decent heuristic. This tends to hold true both for people who pursued white collar careers, or who learned a trade.

You could easily get away with a "gap year" between school and starting a career, but multiple years of screwing around seems pretty hard to come back from. There are exceptions of course, but I can't think of many. One relatively recent example was the rise of coding "boot camps" - where I know of several people who were able to change careers and land high-paying gigs. Or the more traditional path would be serving in the military, getting a free college education, and then going on to a successful career from there.

Has it actually gotten harder to do that recently? It would be tough for me to say without some data. Certainly any time the job market is tight, and there is strong competition for jobs, it's going to put non-traditional candidates at a disadvantage and make it harder to change careers.