It is very important to be aware of this. The market doesn't always continue in the bull market. It will start doing the opposite eventually. So I think that the best thing to do is setting some price goals. It makes things easier for an investor.
It's not just about setting price goals, some people set insane price goals and it makes you wonder if that's actually possible to achieve, I think people expect too much from the market/coin and forget that up is not the only way prices go, if investor will not be too greedy and try setting realistic goals, then they won't be caught thinking whether to sell or hold when a coin gets to the targeted price.