There are tribes where no one cares who gave birth to the kids. We did countless wars and profited at the expense of others but if you fail to account for the soldiers moral it kinda not makes sense for them to make the ultimate sacrifice. We had many religions and some political ideologies where selfishness was not just not admired but frowned upon and undesirable. Most of our quality of life comes from previous generations doing the hard work for us, often intentionally. Try starting from scratch on the "only think of myself" principal and you get something nonsensical like Liberland.
Almost everything was just handed to you. You got a good hand of cards. Almost nothing was the result of you taking care of you.
We are about to have a demographic crunch where we will have massive worker shortages. That is inherently inflationary, and we will need automation which is inherently deflationary if we want to keep the lifestyle we have.
(I also don’t mean to downplay the pain if displacement from automation, it’s a very real problem and a reason I’m a big fan of social safety nets)
but humans are not like plants, they move and immigrate. look at southern europe for an example. Democracy serves a bad deal to younger generations and they know it