Wow, I’ve never met or heard of anyone who thought that (marginal) tax rates should be at 70% for anyone apart from those with annual incomes in excess of $10m, and only then on the income over $10m. I’m not sure where you get this strawman of people wanting to raise tax rates to 70% “for the rest of the country.”
A lot of the people I know in Silicon Valley are libertarian, and they want low taxes for themselves and don’t really care about anyone else, but that might be because they’re wealthy but not super rich. The Democratic billionaires and regular folks seem to be proponents of taxing the very rich (annual income over $10m) more and the average person less, and making life more affordable for everyone.
Many people in Silicon Valley are not earning massive amounts of money, and those that do pay proportionately higher taxes, even without changes to tax rates. I think the stock incentive tax is a good idea for San Francisco: take a tiny fraction from of the income to make the city a sustainable foundation for the growth.
Someone who makes $1m per year might pay $250 to $350 in taxes. I don’t make anywhere near that much (anymore), but I don’t understand how that is wrong or unfair.