So you have to sacrifice one of two people. Either the old who cannot take care of himself, or the caretaker who has to waste their life taking care of the old.
People would and still do deliberately raise some children to be without their own families so that they can be dedicated care takers. Ie not allowing a daughter to marry and such.
Listen, somebody spending years or a decade taking care of a family member is a story as old as time. But let's not pretend it's not an enormous sacrifice.