Cynic's Assumption
Sorry to be fussy, but if the race is fixed, then someone must know either which horse is going to win, or which horse isn't.
There is no other reason to fix a horse race - or anything else for that matter - than to gain some advantage.
That truism leads to one of my basic assumptions about our species:
If something can be fixed, it will be fixed.
Sad, but true. However, let me add that at least some humans are altruistic at least some of the time.
S