Why not you shouldn't see the amount you get you should see the return if you invest 0.003 bitcoin and get 0.0006 in few months the return is really less around 2$ but the percentage is 20% which means if you put 1000 you would get 200$ this percentage will surely encourage your mind to invest more next time
When you don't have a money $1000 to invest then better start with whatever you have first instead of waiting for accumulating $1000 because before reaching that $1000 accumulation you will gain an experience with small amount how these investments work. Once you start then you can add small amount whenever you got funds and can reach your $1000 or more.
You need higher amount to get more profit correct but higher the amount means there is more risk involved also if you invest 10$ and lose 10% that is 1$ but if you invest 1000$ and lose 10% that is 100$ higher amount doesn't mean higher profit it also means higher loss if any
On this case I think the only real risk is to be hacked by the casino. As you said, if you invest $10 and lose 10% it will be $1, but if you invest $1000 and lose 10% it will be $100. The same applies on the another hand what makes the investment stable. You can lose 10% of $1000 today ($100), but tomorrow you can recover 20% bringing you back to the green profit (20% of $900).
Is there a casino that offers such benefits? as far as I know, they have determined how much profit that will be distributed to investors, unless the casino gets more or more of their prediction but I do not think they will ever raise the profit share. sorry if I'm wrong, because I'd rather invest in other investments.