Well i wouldn't consider gambling a type of investment because it is not a sure way of making a profit, but as far as reinvesting crypto to earn more the sky is the limit the crypto market has become more or less the same as the fiat one, you can buy and sell anything using crypto these days, for example you can buy a product using bitcoin and later resell it for a higher price, or you can use some of your crypto earning to buy tokens through ICO projects that might be quite successful in the future, and as i said any thing that you can think of doing using fiat can be done with crypto these days, you just have to bring a need or a innovative thing to the market to be able to make profit from.