It actually depends on what kind of sportsbook you're looking for.The best evaluation would be given by either wikileaks or the site's notes if you follow them.They might be earning a lot though ,not all of them but very few and common one's because those are the one's people use a lot as they're secure as well.
Sometimes i have some question in mind, how can some dealer/owner of the sports betting always win profit on the end of the years?
Actually on sportbetting people can choose who will win on some match. Why their always can get profit from that?
Is not about casino, but sportbetting.
I think because almost everyone after a big win is eager to win more and more. Also the sportsbook looks like u need to have knowledge about who plays, but it is still gambling, a 50/50 percentage chances of succes.
People do not know when to stop and enjoy their profits.