The key thing here is not the number of options but the probability of those options eventually winning.
For example, say a bet was on "Will the mempo roll crit chance"
If Odds were 50/50 for yes and no, everybody would bid No as they have approximately 90% Chance to win.
And those That did bid on yes and we're lucky enough to win would only walk away with a 1:2 win.
I doubt I will be able to build the above as that will be exploited and will cause Significant currency inflation in most streams.
Cases where betting against the house does work is when the odds are fixed and the payout is fixed. e.g. Coin toss, 3 dice craps, roulette etc.
These will come to DeepBot in the near future.
