Simple answer - yes! Diversification is the key to a successful portfolio. You may get lucky and get in Ethereum at $8 this year, but you also have to remember that other cryptocurrencies went up 5x Ethereum's appreciation and more.

In the financial world, diversification helps you lower your beta (risk as compared to the overall market). This is especially important in the cryptocurrency market as many of these cryptocurrencies are illegitimate, or at the minimum will not pan out to anything of great value. By diversifying you can help mitigate this risk. If you hold five cryptocurrencies evenly that you think will be successful, and you're only right about 1/5 of them but it goes up by 401%, you're profitable.