I will invest in Bitcoin and altcoin at the same time but the money earnmark for bitcoin will be higher! Crypto currency is unlike firex that you can predict certain pair against other! Crypto is more dynamic and you may not understand what is driving a price of a coin!
Honestly, that is just more like a sane thing to do. The crypto atmosphere is huge and for anyone who really wants to be a part of it, they must understand everything it entails.
Investing in Alt is not an easy task and it is necessary to find out which is going to do well in the long run and that is not an easy job considering the number of fishes in the ocean. Bitcoin however, is guaranteed at least for now, and anything that would affect it, will definitely end up affecting each alt.