I don't understand this argument. Let's put some numbers up:

Single: income starting at $130k a year. That's 7k/month after tax. Rent a room in SV for $1000 (or Berkeley), and spends $1000/month. That's still $5k/month in savings. If you're senior, that number goes up to $200k a year. That's $11,500. That turns into $9500/month in savings.

Couple: 2 income at combined $260k a year. that's $14k/month after tax. Rents a house in SV or berkeley at $3000/month. Spends $2000/month. That's $9000/month in savings.

etc