You can't discount the pressure on the jockeys either.
When an odds-on favourite is running the punters expect a perfect ride, the trainer and owners also expect a perfect ride.
Racing isn't like that.
The best horse in the race doesn't always win. Punters seem to disregard genuine interference, bad luck in running, a pace in the race not suited to the horse etc etc.

Then they bag the hell out of the jockey.

If the horse was 10/1, they'd just say oh well maybe next time!