Can you go broke with a winning record?
Yes, if each bet is too big a share of your bankroll. An edge shows only over hundreds of bets, and a losing run long enough to empty the bankroll can come first. The smaller the stake next to the bankroll, the rarer that is.
Winning 55% at −110 over 1,000 bets, starting with 1,000: with stakes of 10, 0.0% of simulations went broke and 0.3% were down to half at some point. With stakes of 50, 10.0% went broke; with stakes of 100, 32.3%.
Run these bets in the simulatorThe house edge of every sports bet
A bettor who wins 55%, by size of the stake
| Flat stake | Down to half at some point | Went broke | Average result |
|---|---|---|---|
| 10 (1% of the bankroll) | 0.3% | 0.0% | +502 |
| 20 (2% of the bankroll) | 5.4% | 0.3% | +1,004 |
| 50 (5% of the bankroll) | 30.8% | 10.0% | +2,344 |
| 100 (10% of the bankroll) | 54.4% | 32.3% | +3,669 |
Each row is 10,000 simulations of 1,000 bets at −110, starting with 1,000, seed “cgs”. The link above replays the highlighted row.
Why
A bettor who wins 55% of the time still loses 45% of bets, and losses come in runs. With stakes of 1% of the bankroll a bad run is a dent. With stakes of 10%, being about ten losses down ends it, and over a thousand bets a swing of that size is ordinary. The edge decides where results are centered; the stake decides how far they spread around it.