Successful bettors think that their little black books hold superior "inside" knowledge that makes them experts.
But a new study suggests that majority of horseracing punters will lose money at the track in the long run - there will always be more losers than winners.
Serious punters will often keep track of how well they are doing, in the fond hope of identifying a "winning system."
So says Matthew Browne of CQ University in Australia, whose research group found that the amount of wins required to show that one is doing better than chance is extremely high.
Gamblers who participate in skill-oriented games such as poker and sports betting are motivated to win over the long-term, and some monitor their betting outcomes to evaluate their performance and proficiency.
To investigate what levels of sustained returns would really be required to establish evidence of skill or expertise, Browne's team modelled a random strategy to simulate so-called "naive" play, in which equal bets were placed on randomly selected horses using a representative sample of 211 weekend races.
The results showed surprising volatility, even after a large number of repeated bets. After adjusting for the house advantage, a gambler would have to place over 10,000 bets in individual races with net returns exceeding nine percent to be reasonably considered an expert bettor.
This means that for the vast majority of players, their historic records or data provide surprisingly little information regarding their chances of making a positive return in the future.
Browne said that even sophisticated and rational gamblers, assuming they have achieved moderately good returns over an extended period, are simply unable to recognize that their historical performance most likely occurred simply due to chance.
The findings have important implications for problem gambling, as delusions of expertise are likely to be most prevalent in skill-oriented games and in serious, otherwise rational, performance-tracking gamblers.
The results are published in Springer's Journal of Gambling Studies.