Buy High, Sell Higherer
Easy to say right? 
but when we already bought a coin it will go down. no higherer but in reality it is sell low . Maybe your theory will work when a coin get pumped, or maybe listed in new market.Anyway, OP just said what is buy low and sell high. And for your complaints, there are lots of coins actually that has the potential to grow in the future, you just have to find and research accordingly to their situation. Holding will work in any situation especially if the market seems to drop most of your investment.