I've heard it from Boomers. I've also heard them say they didn't think that until the internet brought out all the "OK Boomer" and straight up blaming everything wrong on them. So they said, fine, if you want to hate on me and be disrespectful, I'll spend as much as I want, I earned it, I worked hard, I didn't get some huge inheritance, I'll spend as much as I want and do all the things I wanted to do and you can have the scraps left over....Not saying that I agree with that but Millennials got ruined as the everybody gets a trophy generation. The real world doesn't hand things to you and they directed their collective hate towards Boomers.
Eh, combined with the "kick them out of the house at 18" and "Pull yourself up by the bootstraps" phenomenon, combined with refusing to acknowledge that the world they grew up in and the world we (I'd say from late 80's/early 90's onward at the earliest as a best estimate) live in is radically different really contributed to the "ok boomer" mentality.
What's the point in building up anything real if you're not going to pass it on to your kids/family? And framing it as abusive to leave it is magnitudes worse as well.
"What kind of father is it that gives his son a serpent when his son asks for a fish?"