Ever go all in 
and have a positive result?
You should never go all in if you ask me because the price can always rise again after you have sold so that would mean that you would miss out on some money. and have a positive result?Sell some and save some that is how you keep maintaining the cycle.
The art of gambling is all in and win, I ever felt that way several times and the result satisfied.
But don't all in if you not sure to win, it's so risky to lose all your capital and do it if you can afford losing.