I will also think of buying the altcoins at the low price and then hold it until the price is higher. Selling some of the coins in the higher price (more than 30% increasing) is good to buy other altcoins then and invest more. I will also leave some of the remaining to hold and sell them at the higher price again. It is one of my strategies. But some newbies actually buy during the bull market and now sell off at the bear market.