Two bettors show you their records. The first one hit 65% of their bets. The second hit 42%. Which one is making money?
You don't know. The number that matters is missing.
The calculation that changes everything
Every odd has a profitability threshold — the minimum win rate to break even. You calculate it by dividing one by the odd.
At 1.50 odds, you need to hit 66.7% of the time just not to lose. That first bettor's 65%, at those odds, is a loss. At 3.00 odds, the threshold drops to 33.3%: the second bettor's 42% produces solid profit.
Win rate alone means nothing. It only makes sense attached to the odds at which it was achieved.
Why this tricks so many people
Because hitting feels good and losing feels bad, regardless of price. A bettor winning nine out of ten at 1.20 feels competent — and is losing money, because they needed to win more than eight out of ten just to break even, and the margin eats the difference.
The opposite happens too: those betting at high odds spend most of their time losing and feel incompetent, even when they're doing everything right.
What's worth looking at instead
Profit in units, which combines both things into one. And for small samples, value against closing line, which tells you if you're catching good prices before the result appears.
When someone shows you only the hit percentage, without average odds and without profit, either they didn't understand, or they understood too well.