It's a cost of living calculation. I earn $x,000 in my current low-COL area. To maintain an identical standard of living that comes out to $350k before factoring in California's high tax environment, and the increased federal taxes.

Don't try to spin San Francisco being the most expensive place to live in the country into me being bad with my money - I'm not. But when you make a high income in a low COL area, it means moving to any high COL area means you either take an effective pay cut in standard of living, or you need to earn an amount that is very unlikely.