It's never worth investing all your money in one coin, even if it's bitcoin! In fact, it's a pretty big risk, because if something bad happens to this coin, you can lose all your money in a moment! And if you invest in different coins, this will give you flexibility (as a rule, the Top 10 coins grow at about the same speed)
I agree. But the problem in splitting your investment is that there will be low chances of getting 100x or 1000x returns. If you invest in a single currency, and if you are lucky, then you may end up as a millionaire. I guess that is what the OP want.