well you would not be able to hedge in the Belmont! if a horse is 2 for 2 he will be 3-5 at the Belmont at least
used to be you could get 11-1 12-1 or so for a triple crown which as hard as it sounds was a a slight overlay for years compared to true odds of wining Preakness and Belmont (because somebody has to win the Derby, and unless they get injured in the Derby will run in the Preakness 100%)...
5-1 yes is horrible.
and -1000 no is probably a fair line.