Nobody has been able to put forth a single reasonable argument for why SF must tear down their homes and put up apartment buildings other that 'because it should'.
And FYI there is no housing shortage in the US overall, there never has been, housing has expanded commensurate with population.
Not only that - housing is relatively cheap in the US.
Of course there is a lot of demand to live in SF vis-a-vis Sacramento, there always will be, but otherwise, there isn't any reason to build a single home unless the residents want that.
If you mean to say 'people have a moral right to live in the city they were born in' - fair enough - but this notion falls apart instantly unless you want to somehow give 'born and raised SF' kids some kind of literal non-market advantage.
If you live in an 'expensive place' then your kids can live there, as long as they are wealthy enough, that's the cost of living in a wealthy place and there's no way around it.
By 'building more to facilitate affordability' - well that certainly would enable more people to live there, but the demand will come from all over not just 'the kids of'.
SF is a small city and it's expensive, if parents want their kids to live there they can literally give them their homes. Otherwise, their kids can get good jobs or live in Santa Rosa.
There is plenty of space in North Cal.
Finally, SF residents can make up their own minds about how they want to do it. More building, less building, it's entirely up to them and nobody else's business.
Yes, there is. In a regime of rapidly increasing life expectancy, there is a demographic certainty of future housing needs.