The tricky situation in crypto is the fact that bitcoin is the best investment if you want both good returns compared to rest of the world and still want to be safe, however its rarely ever the highest return. It means that there are coins which will earn a lot better money for you if you bought them, but they will be riskier than bitcoin for sure, but bitcoin was riskier than gold as well so where does your risk taking ends? Does it end with bitcoin? Or are you willing to risk even more?
If you are, then you could go with some altcoins and they will maybe earn you a lot more than bitcoin could, or maybe they will lose you money. If you are not fine with that, buy bitcoin and wait long term, you will earn more than most other things in financial world aside from some altcoins.
It doesn't matter if you can't get the highest possible return in crypto, I mean if you want to go down that rabbit hole, I am sure that there must be "some" coin doing 100% that day, if you find that 100% one, and buy it before it happens, sell it after it does the 2x, and buy another, and wait for it to do 2x, and keep finding that 100% every day (which I am sure between 15k+ coins there must be at least one that does it) then you could become a millionaire in a month for sure, no matter what you start with.
But, the reality is that we can't, so why worry about not being able to do it, couldn't we really just focus on bitcoin and the guaranteed long term return of that?