If I happen to buy 10 bitcoins at $100 each I would be convinced to sell at the $1k mark. You might ask why? because in my opinion we really don't know how far bitcoin can go and for how long it will stay alive since when bitcoin was at the $100 mark only a few people use it compared to now.
At the time when bitcoin was $100, there was no vision that it could reach 60,000$. I would have sell at 2x price of 200$ and would be happy that i made my money double. But if someone is lucky enough to not sell at 100$, he must be millionaire if he had purchased few bitcoins at 100$.