I think I see it now. You have a parent who has no support system other than you and your sibling(s). Which then forces you to bend over backwards catering to them cuz you love them, they're your parent. But you get resentful you have to do all this work for them though. You think "they wouldn't be able to survive without me". Which then gets extrapolated to "anybody without kids won't be able to survive on their own". And you can't vent this frustration to the person you're caring for so it comes out online.

It's your parent that has basically no support system, not you. But even people with kids can have no support system, having a kid doesn't automatically mean they will care for you in old age.