This leaves out one major factor: they need somewhere to live but that doesn't mean it needs to be the same real-estate market or size. Someone who sells a house large enough to have a family in a major market and retires to a cheaper market can see a very comfortable return. Probably nowhere near enough to make up for the other impacts of the policies people voted for to drive up their home value but it's harder to get people to give equal weight to different factors when one of them will show up directly in their personal bank account.
But considering that people tend to move to a few urban locations, the house prices in eg. florida got very expensive too... yes, they earn a bit more, but I don't believe that single house owners, moving from SF to FL (or wherever) are causing the housing crisis.
I don't disagree that this isn't driving the housing crisis — my point was simply that it's not like many older people aren't strongly in favor of the housing market staying high until they can cash out, because for many people their home equity is the largest component of their retirement plan and they aren't interested in continuing to need to deal with the maintenance required by a single-family house.
Politicians are probably getting paid of by companies investing in housing and buying up hundreds or thousands of houses, because the price increases make it more profitable than many other investments, and (unless there's some legislative action) makes the investment safer than most other high-profit ones (eg. cryptocurrencies).
And the little guy gets fucked in the end.