Well, what else can we do? If we saw our coin plunge we should take the opportunity to accumulate and then just HODL it, if it surges then sell. No one will set at a low price though so what's our choice?
The coins I think better on these buy and HODL strategies are the less volatile one like Bitcoin and Ethereum but if it is an altcoin mostly, you won't be needing to HODL I guess, the fact that most of the altcoins are highly volatile.
It's all about buying low and selling high, that is what investing in Crypto market is, you must follow the market prepare funds when there is a dip and set up a plan on what price you are going to sell it, sometimes it takes a lot of time or a long wait before you can sell, but it's worth it as long as the coin you are holding is good you just have to be patient and wait for the right time to sell.
Exactly holding up substantial coins will be profitable when you intend to sell but w non profitable coins does otherwise, so a more reason to buy at low rate and sell higher to make reasonable gains. This is what makes the market so reliable to traders and investors of long term.