You can bet huge amounts on offshore books that don’t go into the pool
Imagine Northville’s place pool is $2k. A 1-9 favorite will naturally pay $2.10 to place. If you bridge jump $10k on that favorite to place at the track, it would increase the pool size to $12k, still pay 2.10, and you’d take home $10,500 with a win.
If you make a $1k place bet into the pool on a long shot, however, and then place a $9k bet on Bovada (or any comparable site) that doesn’t go into the pool, it will pay more. The on-track place bet would increase the pool size to $3k, raise the favorite’s place payout to around 4.00, and Bovada would pay you out based on that price. You’d make $9k in profit and come home with $18k.
All that being said this is blatant pool manipulation and you’re at risk of getting your funds seized from both entities. So whether it is worth the risk is up to you