If I made 400% on something, I would probably sell half of it, and keep another half at least for a year. That way, both my safety and greed would be satisfied.

(But this is more about psychology than math. For some people this would be the worst option, because if the thing would lose value, they would blame themselves for not selling everything when they had the opportunity, and if it would gain even more value, they would blame themselves for not waiting with everything. So it would be lose/lose from their perspective.)