What about investing in dice sites?
I didn't try that option myself, but from what I read here a few online casinos that allow investing in their bankrolls show pretty consistent results. I consider it a risky business myself (certainly above my tolerance levels) and prefer trading to other types of investments but some folks seem to have raised decent profits from these casinos.
It's a fact that the house always wins in the long run, so if you plan to invest in bankrolls (of course from legitimate and trustworthy casinos only), then your chances of getting some sort of a return are pretty high. I however don't have much knowledge when it comes to how the returns are being calculated, how the payouts are scheduled, whether or not you have your money stuck in their bankroll for a certain amount of time, etc. For me personally, I must at all times have the ability to liquidate my investment. If that's not an option, then it's a definite no go for me.
I remember there was a thread in the Gambling section by some dude investing around 5 BTC in 5 different casinos, and he earned something like 1 BTC in net profits
It highly depends on how long it took that person to gain that profit in order to consider it a risk-time-worthy investment. That 1BTC is a combined profit coming from all 5 casinos, I assume. If so, then there is the question of what casino made him the most profits, and what casino made him lose money (if that happened).