Quote from AAAintheBeltway:
>60% against the spread. Anyone who can do that consistently over a period of time, knows their stuff. Sports betting is an inferior financial proposition, compared to trading, because of the high transactional costs. The risk/reward is skewed against you by the "vig", which typically is 10%, ie you lose a $100 bet, you owe the bookie $110. Plus, unlike trading, you have a defined payoff. So it is purely a winnng percentage exercise. You have to have 52% winners to break even. Sounds easy but it can be frustratingly difficult. You have the spread covered, then the favorite gives up a meaningless(to them) score with a minute to go. You lose.
Most bettors lack the discipline to be long term winners, hence the expression that winners are only borrowing the bookie's money. They'll give it back eventually. I know others do it differently, but for me the crucial aspect is to be very selective in the games I pick. When I was doing the picks thread, I would have weeks at a time with no picks. Boring, yes. But are you doing it for excitement or to make money? For most people, the honest answer is they want to add a little extra interest to the games by having some jack riding on them. Nothing wrong with that, but it's not the way to make money.