I dunno. I think "partying" and "hedonism" are not the reason a lot of us don't want children. I think it's more to do with the fact that so many young adults feel burnt out about humanity. Growing into adulthood and realizing you can't raise a kid in the world you want to raise them in, exactly how you want to raise them (too many rules, stupid other parents, strangers are potential enemies not friends, etc), is a big bummer. Potentially another "selfish" hump to get over? Maybe. Adulthood is a slow process. For a lot of people from upper-middle class backgrounds, full adulthood happens at like 30.
Still not having a kid until I've sat on it for at least a year straight and still think it's a great idea.