Holding altcoins in a long term will be effective only if it has a potential to increase in the future, or promising.
And if that happens there is a probability that you can earn big in the future, however if you hold the wrong altcoin
time will will turn into waste only, so be careful and be wise before anything else.
if I bought 1000 coins for 1 eth, then if these coins grow and my profit is 1.5 ethers, then I sell tokens for 1 eth and I leave 0.5 eth in this coin for long-term