Yes a TFSA offers unlimited upside, and so does a non-registered account by the way. The difference is if you attempt to do a YOLO moonshot and lose all your money in a TFSA its over and you don't get that chance again except for waiting for next year to get that small $6K that you can use to try again. You are better off using a non-registered account for these super speculative plays because more often than not the speculations end up being losers and at least you can repeat that process as many times as you want in a non-registered account and then all your losses from failed speculations can be used to offset gains from your rare winners. It's about risk management. As you get more experience in investing you will realize how important it is to manage risk and the tax consequences around your investments and which accounts (registered vs non-registered) you use because it matters.