Gambling investment is zero or negative sum, considering the house has to profit.
So why are you guys do bitcoin gambling as an investment instruments? OR merely just for the fun, like going to a physical casino.
Gambling investment will always be positive EV.
Because you are investing in the house if you are investing in gambling.
For example, Yolodice and Bitdice are two very popular dice sites right now that accept user investments. Also worthy of a mention are crypto-games, Bitvest.io and Just-Dice(although they don't use bitcoin anymore so that's a bummer).
But if you are the person gambling, sure, it'll always be negative sum.
Can't think of any legitimate casinos that will offer you a neutral EV, because the house edge is how they make profits.