The 100-bet range
Start with someone whose true win rate is exactly the −110 break-even rate: 110 ÷ 210, or 52.381%. Over 100 independent bets, about 95% of their records fall between 43 wins and 62 wins. The same no-edge process can look terrible or brilliant without changing at all.
That is why a 62% screenshot is not proof. It sits near the high end of an ordinary no-skill range. The matching 43% record is just as compatible with the same underlying ability.
Luck is about nine points; a real edge is about one and a half
A strong 3% return on money risked at −110 corresponds to a 53.952% win rate—only 1.571 percentage points above break-even. Over 100 bets, ordinary random movement is roughly six times wider than that signal.
How long does evidence take?
Using a one-sided 5% significance test with 80% power, separating a true 3% return from the −110 break-even rate takes about 6,237 independent bets. That is the scale of evidence needed when the real difference is small.
The arithmetic
At −110, a win returns 100 for every 110 risked. Break-even solves p × 100 = (1 − p) × 110, giving p = 0.5238095. A 3% return solves p × 1.909091 − 1 = 0.03, giving p = 0.5395238. The difference is 0.0157143, or 1.571 percentage points.
The 43%–62% interval is the rounded 95% binomial range around the break-even rate for 100 independent trials. Real betting records can be correlated, which can make the effective sample smaller—not larger.