Of course you should invest in altcoins. Altcoins, especially from top 10, have a great potential for future growth. Just buy Ether and wait for the moon!
I invest in the top 10 coins and I can agree with this post. Narrow the selection to top 3 and trading should be smoother.
No matter how many coins your portfolio consists of. If you trade purely as a trader, then it is not even necessary to trade coins from the top 10. And if your strategy is to buy and wait, then the more collect as many coins in your portfolio