The answer was couples where both parents worked in the tech industry with a combined income of over $300,000. Usually one child and often one on the way, many have houses already further away (Livermore, Gilroy, Morgan Hill) that they are selling.
Now that is unscientific, it is the experience of one broker who is sitting in one open house, showing the house to prospective buyers and gently quizzing them on their financials in order to understand if they are good prospects or not. But I can see other evidence that its probably accurate, the folks moving into my neighborhood fit that profile. A lot of people looking for "good schools" because if you don't pay private school tuition that saves you $15,000 per kid per year you can put into house payments.
My point being that the houses are being listed and sold in a short time frame. That suggests that the housing market is pricing appropriately for the buyers. That there are more buyers than houses pushes up the price and pushes out the buyers who do not earn as much. However, unlike San Francisco, there is a lot of residential building being put up on the peninsula and south toward San Jose. Across a wide spectrum from apartments to condos to single family attached, and single family detached. Sunnyvale has a ballot measure (https://sunnyvalepubliclandsact.com/) that is seeking to limit how the city can transfer park land to developers to turn into houses (or hotels, or office parks). That measure is an artifact of all the building that is going on.