Some of this is just obvious it's MUCH more expensive now than it used to be. I saw a graph on FB this morning I don't remember the exact numbers but something like if you work at a minimum wage job you had to work 100 hours a week to afford college in the 90's and now have to work like 5000 hours. Rent etc all the same thing.
yes there are certainly young adults who just don't want to pay for everything too I see that as well, but I see lots who just barely make it by. One of my buddies at work is I think 24 or 25 not sure how old she is. College degree, works 2 jobs fulltime one part time another she works 60-70 hours a week. She just had to move back in with her parents to afford to pay off her college loans before she is ready for social security. And I see that pretty regularly.
It does suck that parents are giving up their retirement savings but it's a function of how the whole system is going IMO.