I know you can't believe it until you live there, take a gander on Zillow for Palo Alto. Here's a random selection for you, 2100' rancher from the 70s, dated and a bit ugly, $2.9M (
https://www.zillow.com/homedetails/878-Miranda-Green-St-Palo-Alto-CA-94306/19524026_zpid/). And that's not out of the ordinary at all, anywhere on the Peninsula. That's $130K on your mortgage alone, plus come up with a $580K downpayment. When I lived in Palo Alto we were paying $50K a year for childcare for our 2 kids, and that was at subsidized school child-care that we were lucky to get into because all the rest of the childcare within a 30 minute radius had a 2 year plus waitlist, and was more expensive. Again, I don't blame you if you are calling BS on this, but it's insanely expensive beyond what you can believe even when you live there, and that's without trying to look like you're a successful CEO. So $390K is enough to get you what $100K gets you in FL, or VA, or even what $150K gets you in HI having lived in all those places. It's not chump change, but I guarantee there's no "wealth" there.
The Kalanick story is true, and in fact I also exited my first company by selling my shares to our investor, so it's not unprecedented. It's just rare. Not anything approaching Bezos' level of success but I do still have my car with 150,000 miles on it and live in the same house, in my experience wealth is far more valuable for the freedom it gives you than the stuff it buys.