I think you just answered your own question.
Realistically, I could place 100 satoshi wagers on every thing paying over 100:1 and if one or two come up, then I've blitz the competition - no?
If your declared bankroll is 0.005 btc , 100 satoshi wager is only 0.02% of your bankroll and even if you managed to hit 100x with 100 satoshi wager that would be + 2% ROI for you.
Someone could have easily blitz through you with 5% of their bankroll bet at 2x betslip. Its much easier to hit a betslip with the odds range of 1.5-2.5x rather than 100x odds isnt it
I think this post post from Venalli pretty much sums it up. This ROI contest is pretty similar to Directbet's tipster championship if you are familiar with that contest
1)for 0.05mBTC bet(@5x) with bankroll 1mBTC, Your gain would be 20% but lets say you have bet your whole bankroll(1mBTC) on that 5x and won. For your ROI, it would be considered as 5% of your current bankroll. Which would be 0.05mBTC.. and your ROI would still be considered the same 20%. ie. Your new bankroll for any future bets would be considered as 1.2mBTC in both cases.