Holding too much coins will make your concentration be scattered and even you may miss the opportunity to sell them with the good price if you can't track it regularly
and maybe for them to hold lots of coins, the more chances they get, so they hold a lot of Altcoin. if you hold a lot of Altcoin, of course you have to be able to monitor all the coins that you hold so that you don't lose good moments and you have to monitor their movements often.
Altcoin can give good results so you hold a lot of things, you have to be good at managing, so you can get more profits.