You have three options in this instance:
1) You just don't care how tight the price gets, because (unlike every other bettor in the world) you absolutely, definitively know you are going to get paid out, so even if you only make 5 cents on the dollar, you are betting a sure thing (and can keep doing it over and over - how much would you make betting against Smarty Jones in the Belmont?);
2) You lay wagers on the other horses in the race so that the entire market moves up; Smarty Jones's price doesn't collapse, and you still get paid out at $3.40, or;
3) Place your bets in a fixed odds environment (Vegas, Macau, UK, Gibraltar).