I also think there is a misunderstanding here. In this kind of bet, the track takes a cut. In other word, your 10-1 odds are calculated on what's left after the track took a cut.

I simulated this myself on the HK tracks: if you bet randomly _and_ don't ignore track take, your expected return on the long run is precisely $BET - $TRACK_TAKE, which was about 80% in HK. ie: you lose 20% of your money on average on each bet.