Investing in altcoins is about knowing how to ride the wave, and is the best way to multiply your Bitcoins, but no one says it would be easy, users need to buy when the price is low and sell when the price is high, and to do this we need to follow the market signals and the media news for relevant events. For example, if we see in the news that Elon decides to incorporate Dogecoin to Twitter, then is time to buy doge because it will bump.
Buying Altcoins and hold for a long period is really risky, and personally, I don't recommend it. But remember, high risk can bring high profit.