Well the way it works is pretty simple. You can invest that in some new and up coming Casinos. If they are still around in 1 years time you stand to make multiples of your investment. However since most up and coming Casinos usually have capital issues, its very easy for a huge whale gambler to come and clean them out. Like that "fun-casino" which doesnt have enough bankroll to issue deposits.
Its much safer investing in larger casinos such as PrimeDice who will never have liquidity issues, however PrimeDice doesn't have a program to invest in. So you are pretty much stuck.
That's actually not great advice. You're taking big risks if you're investing in new casino's, they have no proven track record.
How much you make depends on their house edge and the percentage they pay out to investors.
Crypto-Games is a large gambling site, that has been around for years. They're also very transparant on how much they pay out to investors and you can still invest for as little as 0.01 BTC.
Don't invest in new casino's, stick to the established ones!