I think you'll find (in general) that the people most opposed to new housing (long time residents) are the ones paying the lowest property taxes, due to Prop 13.
Newer homebuyers who are paying taxes on the actual market-value of their homes tend to spend far less time at Supervisor meetings.
Actually I think you'll find that your guess is completely wrong. Long term residents don't face as much issue with new housing because they already have made the lion share of their gains. Newer homebuyers are the most at risk if higher supply causes their 1.5M house to drop to 1.2M because of higher number of houses in the area.
This is all true of course, but it's not what I said.
While it might be more economically rational for newer homebuyers to be the ones fighting development, it hasn't been my observation that they are. Obviously I could be wrong, I'd love to hear stories of rampant NIMBYism among the newly-landed.
My anecdote counters your anecdote. I find that the newest members of a neighborhood are the ones most likely to fight new development. The older people care but they don't have as much vested interest because they don't lose as much money.
Newer homebuyers who are paying taxes on the actual market-value of their homes tend to spend far less time at Supervisor meetings.