Let's assume the odds are fair such that the odds of all horses sum up to 1. Betting on all other horses would give you 1:1.02 odds whereas they should have bee

Let's assume the odds are fair such that the odds of all horses sum up to 1. Betting on all other horses would give you 1:1.02 odds whereas they should have been 1:1.01. While there is no way to answer for sure how many races you would have to bet on to make money, we can look at the probabilities. There's a 95% likelihood that the horse will lose 5 races in a row. If you start with $100 and reinvest your winnings every time you'd earn a profit of $10 with 95% likelihood, meaning there's a positive expectation value. On the other hand, if the 1:50 odds were right, the probability of it losing 5 times in a row would be around 90%, leading to a neutral expectation value.