[jfengel]

If other countries were that friendly to startups, people would already be doing it.

Startups get done in the US because of the network effect: this is where the other startups are, and where the people who fund startups are. It's hard for them all to de-camp at once to a different country, especially since most of the countries they'd want to go to already have higher taxes than the US.

There's probably some limit beyond which people would leave anyway -- presumably, lower than 100%. I don't know if they'd leave over 20%. But I bet you could demand a 5-10% stake, and get many threats but few actual departures.