Many buy bitcoins and altcoins, they wait when the price will rise and sell. What other ways do you know?
Strategies can be completely different. If you are a trader, then you trade and earn on the volatility of cryptocurrencies. If you invest for a short period, you buy cryptocurrency when it is close to its minimum and sell at the peak of growth. Or you are a long-term investor and hold cryptocurrency, assuming that in a few years it will cost many times more, buying more during the decline and expanding its cryptocurrency portfolio.