Why? You are throwing away half of the board where there could be value. Follow me on this example. If the Giants were playing Zona and Schmidt was going against Fossum, and the line was SF -120, you are saying I can't bet on this because I only play plus money. Now obviously this wouldn't happen but there is value to be found with favorites. Last year the Tigers had about a .265 winning percentage. They lost more units than any other team and they were the dog 99% of the time.
Money can be won with favs
Hitman