I can explain the perspective as someone in the adult child's position. I'm not asking anyone to agree, have a change of heart, none of that. You obviously don't need to explain yourself to a stranger. But it seems sad to think of how many people are going to end their lives estranged from their families or without their esteem and won't understand why, so here's me trying to explain a few whys.

First, we remember our childhoods. We remember the super involved grandparents who provided our parents with free on-demand childcare and consistent, reliable after-school care. We didn't forget how much of a village or how much help our parents had, but it really seems like a lot of them have forgotten and replaced reality with some bootstraps fantasy. They've convinced themselves they were these hyperindividual superparents who "sacrificed so much" without any help from anyone, when in reality they had unquestioned access to the familial support that they call us entitled for even suggesting. But we didn't get the idea that family helps family from thin air, we got it by watching our grandparents be those kinds of parents (and from the 80s-90s level of household chores we were required to oversee to contribute to the family). The idea that family owes one another something died with our parents, it wasn't borne of our imaginations.

Second, the quotes around "sacrificed so much." Most of us under discussion here have kids of our own now, which means we're no longer just taking our parents' word for it that they "sacrificed so much" for us and trusting that we'd understand once we had kids of our own. I have my own child now, and any benefit of the doubt I had been extending is gone. My child is not some burden I'm "sacrificing" my life for. I hope to god I never, ever, lead her to think of herself as a burden or to feel guilty for existing. I chose to bring her into this world because I wanted very much for her to exist. I asked for this, not the other way around, and I am so grateful to her for making me a mom. I hope I'm a good enough mom that she'll be grateful for having me, too. But simply bringing her into existence and then maintaining that state won't cut it for making me a good mom. Providing her with food, shelter, clothing, medical care, and education is literally (LITERALLY) the legal bare minimum that I owe in exchange for the decision to have my her and isn't some spectacular, Herculean feat worthy of worship. Entirely too many of our parents martyr themselves for putting the bare minimum into a life choice they made for themselves, and we're seeing just how selfish that view is as we come to realise that that's not at all how we see our own children.

Finally, speaking of selfishness and the new perspective that parenthood gives us, a lot of us are coming to realize just how deep that selfishness runs in our parents and how callous it makes them. If someone suggested that one day I'd be jetting off on cruises or weekend warrior excursions while my child struggled to make ends meet, I would be deeply offended that they thought so little of my character. I can't imagine living it up on resources that I've specifically chosen not to use for the betterment of my family (that, again, I very specifically chose to have). It would all tatse like ash in my mouth. And I didn't realize or appreciate that until I had my own child. Until then, I extended the benefit of the doubt that of course anyone (parent or not) has the right to do with their money whatever they want. I hadn't built the mental bridge that the things we want to do and choose to do are still a reflection of the kind of person we are, regardless of whether we have the right or not. Being able to do something doesn't mean someone isn't selfish for doing it and "having the right" doesn't mean others are required to respect them or hold them in high esteem for doing it.

So that's some of the why, how some of us see it. We've spent our lives watching our parents gobble up help like they'd die if they were left on their own for even a day, then we listened to them complain endlessly about how hard done they were, then we found ourselves in the position they were in without even a fraction of the help they reveived, and we realized that our parents were actually the selfish and entitled ones all along. They haven't become selfish because this is who and how they've always been. We've just stopped pretending they're not, now that we can confirm definitively from the other side that they are.