It's pretty simple. They give you the wrong odds. For instance, let's say there are two outcomes in a match and both are equally probable. So the chances are 50:50. Now the odds should really be 1/1 (2.0 in decimal system) for both outcomes
psk. However, the bookies only give you odds between 1.8-1.9, keeping a margin of 10-20% for themselves. That's how they ensure they always win.
If you want the fair odds, you will have to go with an exchange system. In case you didn't know already, in an exchange system, people bet against each other, not against bookies. Meaning they get the real odds, instead of the unfair ones set by the bookies. That's why you always get better odds at an Exchange than a Sportsbook.
