Sports betting odds are set by a bookmaker. This can be the casino or any other place where you bet. First, a line is drawn based on the analysis of the outcome of an event (be it a match, race etc), then the line will move accordingly to how players place their bets.\r Basically, the goal for the bookmaker is to attract action on both sides of the betting line which’ll make their risk as low as possible – not to give players an accurate picture of reality.