It's obviously not impossible for someone to turn down a billion dollar offer because they think it's not enough, or to maintain control over their company. But

It's obviously not impossible for someone to turn down a billion dollar offer because they think it's not enough, or to maintain control over their company. But I think people drastically underestimate how easy it would be to not sell out and walk away. The kind of people who will look at that offer and say "no thanks" are far and few between. There is a non-trivial chance that most of us have not met anyone like that.