It depends on what amount and what altcoins we are talking about. Everything is relative, you can't become a millionaire with bitcoin if you have 1000$ in your account, but 1000$ is sometimes much more pleasant than the lack of it, when you invested in the wrong altcoin and it lost 99% of its value. Investing in altcoins and skillfully fixing the profit from their acquisition is a professionalism and most market players have no idea what altcoins they buy, what to do with them and when to sell them. So at a distance it turns out that it is bitcoin investing that will make you a millionaire much faster even with $1000 than some altcoins that only take your money away.