Let's supose you bet in an odd of "1.85". Knowing your risk is "1.00", we divide 1.00/1.85 that's equal to "0.540...". That means that, in this case, you have to win at least "54,1% of your bets to be profitable. But your chance calculated by the bookmaker is 50% and there is no reason to believe that they are wrong, they have the best brains, best technology and a lot of money, they make theirlives by that activity. "50%" of times you win and earn "0.85" and "50%" you lose and when you lose you pay "1.00". Let's see how our math will ends: 50/100 * 0.85 = 42.5/100  ;  50/100 * 1.00 = 50/100. So in this case is expected we lose 7.5% in each of our bets. That is no occur on each bet, but in the long term it will. That pattern repeat in all odds, your lost is just the consequence of all that math.