Most of old altcoins are already high and you can't make a big profit unless you invest a big amount.
I advise you to invest in new and cheap altcoins related to promising projects. They still can make rich with a small or moy investment.
This is true to some extent. I don't believe bitcoin will still grow 10 folds but still it has a good potential to rise.
And other popular currencies like ETH and XMR and LTC still has a good potential and are relatively risk free.
Imagine you had ethereums from $5 price and then you're selling it at $800 and this would be amazing. In this case, only few thousands wold make you a next millionaire. It's easy when you think about it.