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.
there is nothing wrong with the altcoins specially what you are mentioned for yes i believe that also that some of altcoins have the potential for you t be a millionaire yes it is hard to believe for but always remember that not only bitcoin has that potential cause as far as i know there is a lot of there that had been millionaire by this currency , by altcoin.