[user104658]

Too long Kirk, didn't read. I've worked as a manager for a (very busy) bookmakers for five and a half years. Rank outsiders win every day. 33/1 shots win every day. 100/1 shots win several times a week. Last week a £3 lucky fifteen return thousands because all four horses won, none of them at less than 15/1, one at 50/1. In the last year, I have taken / processed over 100,000 bets. That's me, personally. So yeah... That's my sources. First hand experience. If you like, I'll come back to this thread in a week with a list of winners at odds of 33/1 or greater, in races with 6 runners or more. I'm just generous like that I suppose.

7/4 alongside not one but two 7/2 shots is not a strong favourite, no. A 6/4 with nothing else in the field bigger than 4/1? Thats an "almost certain". But again, an 8/15 shot will lose to a 7/1 2nd fav as an everyday occurance. This is why the bookies always win.

The professional gamblers you are talking about who make a career out of these things have detailed and specific knowledge of the horses, courses, trainers and performance in training. I did mention "insider knowledge". Another protip: the odds makers fiddle the odds to make horses that they know are going to run poorly look like a favourite, and better horses look like outsiders, because a huge majority of everyday punters bet on 1st/2nd favs habitually. That's why those in the know are dangerous, and that's why anyone betting £100+ at around 6/1 or greater regularly will find themselves having their stakes or ability to take a price restricted.

Average punters who do not have this insider knowledge - and who are not involved in odds fixing rings online - do not have sustained wins over time. Period. The reason for this is that psychic abilities / mysticism / future prediction is nonsense, and because lucky streaks are based purely on coincidence which can be completely and easily deconstructed with a basic understanding of statistics. To put it simply: thousands of things are happening to almost 7 billion people every day, running to a total of several trillion "events per day". That several of these events will coincidence in ways that seem highly improbable is not strange, it is not providence, it is not paranormal - it is mathematical certainty.