> if SF wants to tax excessive income disparity, I say, fair enough.

None of the billionaires here made that money from their salary. This will not touch them at all.

> If they do leave, I don't see that as a bad thing.

Chasing away jobs and the tax base will not end well. There is a decent chance SF enters a financial death spiral from its pension obligations. At the very least, massive cuts are in order. SF will not be transformed magically back to the year 2005, but it could very well wind up back in the 70s.