One of the most common fallacies for casual bettors is that “all you need to know to win” is “who the house needs.” Find that out. Bet on those teams, and you’re going to be a winner because the house wins over the long haul.

The short-term danger of that approach was evident this past Sunday when the public crushed sportsbooks in the NFL. Las Vegas oddsmakers told VSiN it was their worst day of the calendar year, and one of the worst football days ever. Aggressively fading the public last Sunday would have drained most of a casual bettor’s bankroll in a matter of hours.

But, even long term, it’s a bad strategy.

Casual bettors seriously underestimate the power of vigorish at high volume. Vigorish is the “surcharge” that penalizes all losing bets. You have to risk 11 to win 10 on most point-spread wagers (or anything in that ratio). When you say it that way, it doesn’t sound like much. Just a buck. But, at high volume, it’s the key factor in a sports book’s profit.

Imagine you’re going to apply this strategy because it sounds so foolproof. You find out the general public has loaded up on two TV favorites. For the sake of example, let’s say the sum of public action adds up to $550,000 to win $500,000 in each of those games. You bet the other way on the underdogs because “the house always wins.” With your casual budget, you risk $110 to win $100 on each. Then the games split out — one blowout, but one upset.

Sports books earn $50,000 with the split, but you lose 10 bucks.

You may have heard the break-even rate for 11/10 vigorish is 52.4 percent. Sportsbooks are on the other side of that. They only have to hit 47.6 percent to win. If point spreads do their job of creating virtual coin flips, you’re not going to win by betting on “who the house needs.”

Worse, it’s not as if “dumb money” (to the degree it exists) is involved in every game. Particularly in college sports, the public tends to focus on big TV games in major conferences, while sharps (professional wagerers) often step out on lower-profile games in lesser leagues. The seemingly brilliant strategy of betting who the house needs can be a killer in these off-the-radar matchups that are in the sharps’ wheelhouse.

Fading the public likely will stick you in that 50/50 window that slowly eats your bankroll. Fading sharps probably will hurt a lot worse.

One of the hidden penalties of betting who the house needs is that it’s a passive approach that keeps you from attacking vulnerable early numbers. Oddsmakers aren’t perfect. They have to post an opening number in every game on the board. Sharps try to find mistakes and pounce on them (part of the reason they’re called “sharps” is they help “sharpen” the line).

So, for the perceived “advantage” of finding out who the public’s betting late in the week and on game day, you forfeit any opportunity to bet softer opening and early week numbers.

There are no shortcuts to beating the market. The human brain seems designed to search for shortcuts, particularly when math is involved. Sports betting’s historical 11/10 vigorish turns what seems like a small penalty to small bettors into big profits at high volume for sports books.

Worse, other propositions such as futures (odds to win a championship, for example), parlays (needing to sweep a set of bets for a large payoff), or teasers (getting extra points in your favor but needing to sweep) all have an “effective vigorish” of even larger than 11/10. It’s harder to win those than it seems, and the financial penalty for losing is larger than it seems, too.

Knowing who the house needs in those doesn’t help you either. And, it can create more bad bets. Ask all the baseball bettors who took futures shots on the Indians, Rockies, or even the Cardinals in September because “everybody” was betting the Red Sox, Astros or Dodgers.

Sharps focus on player and team skill sets, game conditions (such as weather, travel fatigue, back-to-back fatigue in the NBA, ballpark factors in MLB, etc. … ), then they use what they learn to create their own lines. Pro bettors have their numbers before anything hits the board. That way, they can attack mis-priced openers. They don’t wait around to see what the public is doing. That allows them to better protect and grow their bankrolls.