You can't become a millionaire if you're measuring your wealth in dollars because Bitcoin can't get to $1 million in this bull market. If you also invest that amount in Ethereum, it can't make you a millionaire as well. The only way you can become a millionaire in this bull market is by investing in altcoins.
We have good altcoins that you can invest in and we have those you can invest just for the purpose of riding the hype like memecoins. $Pepe is the recent and trending memecoin and I feel it'll become very popular in the next bull market. You can buy it and make millions of profit but be careful.
Don't invest more than you can comfortably afford losing if the coins fails to reach the peak we're expecting due to other memecoins like Dogecoin and Shiba Inu reached those prices during their peak. Pepecoin might go in the same direction or have a different reaction from the community not believing it.
It depends on what amount and what altcoins we are talking about. Everything is relative, you can't become a millionaire with bitcoin if you have 1000$ 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.