SP,
Commonly accepted (at least among many strong numerical handicappers) is that 1 point is worth 5% edge. If you win 80% of your plays, your return is 58% on every dollar you bet. Divide 58%/5% and you get 11.6. That means if you had the absolute most perfect computer program in the world, and such thing really doesn't exist, then you would have to have an 11.6 point edge on your bets to win. And that would be if the games were decided purely on the basis of perfect outcomes. If the ref makes a couple bad calls, if the star player makes a couple more turnovers than he is supposed to, if one of the players is playing sick or hurt...it won't be a perfect outcome. In short, to offset these imperfect games, you would have to have an even higher edge to win 80% because you figure to go 50/50 when the games aren't truly handicappable. So maybe 15 point edge would do it.
So you tell me, how many times could a perfect computer spot a game that the line was 15 points off? Maybe once every two years?