That is true, hodling your altcoins for a long term basis is a very good strategy and option and wait for the right time that the altcoin is pumping before selling your hodl tokens.
It is a good strategy for a few choices but not for all. If talking in general, this is a bad strategy if you'll include those altcoins that are not really known and good.
The manipulators can easily send those tokens to crash if you're holding them and you have no confidence in holding them. You have to adapt the market so that you won't be the one that will be struggling with its dump if the majority of its whales starts to dump the token that you hold.