you do not need to take a long-term, there is a lot of coin for a low price and has a fast movement. you can see a few coins in poloniex, very much altcoin low prices with fast movements. so it can take advantage of the coin with a brisk trade.
If you feel you're profit by holding the coins you buy , you can sell it without regret because you already profit from that coins.
And you can buy again after the price dump , or your own when for buy it.