What most of them fail to realize is that, no matter the percentage increase a coin makes for you, it is not your profit or money yet until you take it off (take Profit). When investing in any coin, you should have a clear strategy, (i.e. an entry price and an exit price) and once the market reaches your exit price target, take a good percentage off to pay yourself, do not let greed set in. The market is very unpredictable and can turn on you anytime, but if you pay yourself, you won't have any regrets.
That strategy is very conservative, and it has some positive and negative side.
The good side is that you will get your 50-100% gains and you will get out, taking a high percentage of your investment. I think this is good strategy if you are dealing with shitcoins which are just pumping without any fundamentals.
On the other hand, if that coin just hit 2000% 2 years later you will highly regret. I think this often happen to bitcoin and ethereum, which are the projects with better fundamentals and investors should have a long term strategy with those coins.
Personally, i believe it is a good idea to sell a small percentage of your gains every time the coins make huge pumps.
You can sell about 1% every time the coin gets a 100%, or sell 10% when it makes 1000%.
I also like to sell all my altcoins when they pump to trade them back to bitcoin, so I keep track of COIN/BTC ratio all the time.