They do it for greed. They do it to make money, those in the know get on early with FFWin, FFplace, FFF3 etc. A horse with little form could be paying $20+, those in the know stick a few hundred on it, price drops, they stick more on it. They could end up getting a few thousand on at a good price. Eventually, the bookies will drop the horses price because of this but those in the know have already got on at the right price. Profits galore and stake money too. The love of money is the root of all evil...