Another interesting point is that a lot of the major tech companies are incorporated in Delaware, not California, where taxes are lower:
Secessionists point out that California receives only 94 cents in federal spending for every dollar it pays in income tax. Yet leaving could sever crucial ties to the rest of the country. Southern California gets most of its water from the Colorado River in Arizona, and the entire state’s natural gas and oil supply arrives through pipelines coming from Texas. Many California-based companies are incorporated in Delaware, for the lower tax rates.
https://www.bloomberg.com/view/articles/2016-11-11/silicon-valley-s-secessionist-fever-dream
Add water rights, gas and oil supplies and trade ties with the rest of the US, which would be soured and need to be negotiated, and there's an extensive hill to climb. It's not as if California could leave the US today and nothing would have changed for it. It'd be hurt.
This talk is just people being angry with the outcome of the election. Democracy is funny that way, it leaves a lot of people pissed, but it's the system the Americans chose and it's the system they want to live with. Like past protests after elections, these will die down too. They've just got a bit more life in them and there's more steam to vent this time around.
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I always wish my American friends the best, even if I disagree with their choices, but I sincerely hope this situation works out for you guys, or else it's going to be four long years of this: