This is true, altcoins or rather a good number of them are really something else. 2018 is even far, let's talk about this year alone, going through many telegram groups you will see that in many projects today nothing is happening, no presence of the team, no development, no platform updates and so on, and you will just be wondering what the fate of those who invested because they believed will be. Or about those who are still holding, what they will be thinking of. Most telegram groups today are dead, spam messages here and there, while the coin keeps dropping in value.
Therefore, having all these in mind, I totally agree with you, profit is profit, and it's good to learn when to sell and exit a project. On the other hand, there are still altcoins which are worth holding, this starts with Ethereum, BNB and so on.