Most bettors overlook just how much randomness shapes results – even when they have a real edge. This post uses Monte Carlo simulations to illustrate why small short-term samples can mislead, and how both the edge (your percentage advantage over the market) and betting volume dramatically reshape long-term outcomes. Let’s dig into the data behind variance and expectation, and see why even sharp bettors can lose for long stretches.
Understanding the Experiment
Using 1,000 simulations, we tested outcomes over 10, 100, and 1,000 bets, adjusting edge from 0% (no advantage) to 4% (outstanding). Results capture the probability of different outcomes: being in profit, deeply ahead, or deeply behind. The lesson? Edge and volume both matter, but neither can eliminate chance entirely.
10 Bets: Randomness Rules
| 0% | 1% | 2% | 3% | 4% | |
|---|---|---|---|---|---|
| In the Green / Even | 63.1% | 63.1% | 63.1% | 63.1% | 63.1% |
| In the Red | 36.9% | 36.9% | 36.9% | 36.9% | 36.9% |
| Down 3 or More Units | 18.5% | 18.5% | 18.5% | 18.5% | 18.5% |
| Down 1 or More Units | 36.9% | 36.9% | 36.9% | 36.9% | 36.9% |
| Up 1 or More Units | 38.5% | 38.5% | 38.5% | 38.5% | 38.5% |
| Up 3 or More Units | 16.0% | 16.0% | 16.0% | 16.0% | 16.0% |
After just ten wagers, even a solid edge doesn’t shift results much. About 37% of bettors will be in the red, regardless of their edge. The unpredictable nature of small samples means variance dominates, and “running bad” isn’t proof you lack skill.
100 Bets: Edge Starts to Show
| 0% | 1% | 2% | 3% | 4% | |
|---|---|---|---|---|---|
| In the Green / Even | 55.7% | 55.7% | 64.6% | 72.5% | 78.9% |
| In the Red | 44.3% | 44.3% | 35.4% | 27.5% | 21.1% |
| Down 10 or More Units | 17.5% | 13.0% | 8.5% | 5.7% | 4.1% |
| Down 5 or More Units | 27.5% | 21.1% | 17.5% | 13.0% | 8.5% |
| Up 5 or More Units | 30.0% | 37.2% | 46.0% | 55.7% | 64.6% |
| Up 10 or More Units | 18.0% | 24.4% | 30.0% | 37.2% | 46.0% |
With 100 bets, higher edges begin to assert themselves. At 2% or better, your odds of finishing in profit leap ahead. Still, variance remains – over a fifth of bettors with a 4% edge will end up losing five or more units.
1,000 Bets: Volume Unlocks the Edge
| 0% | 1% | 2% | 3% | 4% | |
|---|---|---|---|---|---|
| In the Green / Even | 50.9% | 73.9% | 88.6% | 96.2% | 99.2% |
| In the Red | 49.1% | 26.1% | 11.4% | 3.8% | 0.8% |
| Down 20 or More Units | 26.1% | 11.4% | 3.8% | 0.8% | 0.4% |
| Down 5 or More Units | 44.5% | 20.5% | 9.2% | 3.2% | 0.7% |
| Up 20 or More Units | 28.8% | 50.9% | 73.9% | 87.8% | 95.6% |
| Up 50 or More Units | 6.4% | 19.5% | 39.0% | 60.9% | 81.1% |
The story changes when you scale up. With an edge and enough bets, statistical luck gives way to repeatable winning. At 3–4% edge, nearly all simulations finish ahead, most by a wide margin. Yet, no edge is a sure thing—rare, prolonged downswings still occur.
Takeaways
Even with strong analysis and a significant edge, outcomes over small samples rarely match expectations – and even with big samples, occasional losing streaks are mathematically guaranteed. The surest path to success is combining both a real edge and substantial betting volume, but even then, patience and good risk management are essential. Sports betting is a long game, and variance is always along for the ride.