I know what Chrome was saying is correct:

Originally Posted by Chrome Prince
"Because you lose less betting on odds on favourites.
Longshots, you have to overcome 30% plus percentages against you versus 5% to 10% against."

But only as far as overall stats. go.

We don't bet 'overall', we bet 1 race at a time and in that situation, the percentages are meaningless, regardless of how many bets we have. Also, a $5 loss on an odds-on favorite is exactly the same $5 loss bet on any other runner. Every race bet is separate from any other bet. Their is no rule that says a longshot punter will lose more than an odds-on punter. It depends on the punter. If I back a horse at say $10, that's not because I think it is a 9/1 chance, it's because I think it's a 3/1 or 2/1 chance!