Not all crypto users are luckily enough to trade too in which i have lots of friends that do the trading but as market price is really unpredictable then when they buy the dip it dips even more. Holding is good if you are holding the promising coins but if your coins are crap then better sell it as there is no really hope of keep on holding them.
Interesting strategy, when all of the market is falling, trade in lesser known coins. I think they won't be able to follow the whole falling trend and will be kept afloat.