I'd rather buy it some bitcoin than to invest it in a gambling site, because it is still guarantee you that you will get anything in return, it is like 50 50
It is not really 50-50 because casino has house edge and expected profit in long run because of it.
while if you are going to invest your money into bitcoin, the possibility of having a profit is 100% sure
That is also not true, speaking about investment 100% doesn't exist.