I agree with what your saying Chrome, but a horse's chances of winning is not decided by price moves, if they did denote winning chance %, all favorites would win, but 7 out of 10 don't. Why? Because of all the unknown factors involved.

Personally, I believe the way to profit is arbitrage betting [isn't that what you do?], but for most punter's with small banks, they would probably keel over from boredom using that betting style unless they were into accounting as well as their interest in horse racing [nothing wrong with that] and sure, that's what bookies do, but not punters.

For most punters the challenge and excitement is beating the bookie and the odd big win, even though the bookies will mostly win in the end.

Punting and arbitrage are two different animals serving two different endeavors.