Two other aspects–MP may be simply getting older. A lot of the houses were built in 1960s, and those people still live there.
Also, I wonder if more $$ means more people using private schools. That said the parochial school we have one kid at has had a lower enrollment the last 2 years for Kindergarten. But there are a lot of private schools opening up on the peninsula.
It’d be interesting to compare it to Redwood City which i was under the impression was getting more crowded.