Not true in the case of shareholders. For example, if MZ became a Nevada resident and quit working for Facebook but still had all of his shares, he would not be subject to California taxes when he sold them. Even if he continued working or consulting for FB, California taxes would likely only apply to the income or options derived from that work (though California has some onerous and complex "substantial nexus" rules that may apply if he still worked there, yet another reason to simply not startup there in the first place).