What's the income profile of people buying $3M properties in south bay?

I bought the most expensive lot in Menlo Park in 1989 for $505k. 12 offers. Was offered $5k for my slot. The lot was advertised as 10k SF turned out to be 8300sf.
Lost money at $1m for a big spec home. Recently sold for $4m. I would guess that lot is worth $2.5m today
5x in 29 years.

5x in 29 years is not very impressive for land

We overpaid. Asking was $425k. But there was a buying frenzy, like today.

The house only went up 4x . With 20% down IRR is 20x