You invested in a ICO or IEO project at 1$ per token or coin and the price surge up to 3$ but because you see potential in the project you decide to hold and after few months the price goes down to 0.45$ and after four years and the token surge back to 3$, my question is why the wait? You hold a coin for years just to go back to it's ATH (All Time High) ? And most times majority of coins don't go back to their ATH ever again, what could you learn from this? Never ever hesitate to take profits, even if the project is the best ever, take profits, invest again when price is down because believe me, the price will surely go down
if humans are programmed to see the future won't we all be rich?
The first thing I can say about this topic is that you can never know when the price will reach the ceiling. The price can double in one day and fall even in one night while you're asleep, you can never know.
Investors should learn how to take profits by selling in tranches. Don't let greed take you. Once you feel that a profit is enough, try to sell 25% or 50% (or more) of your position to lock your profits, this will ensure your profits in cases where the price falls.
Just don't sell everything because you still want to have a position in cases where the price jumps higher.