According to Arthur Miller in his introduction to Thomas Putnam in Act I, Putnam has a number of grievances with various individuals in the town. In addition, he "regarded himself as the intellectual superior of most of the people around him," and so when they deterred him or his candidates for public office, he grew resentful and "vindictive." Moreover, years earlier, he attempted to break his father's will because it left more to a stepbrother than to him, but "As with every other public cause in which he tried to force his way, he failed in this." Miller claims, then, that it is unsurprising to find that so many of the accusations against other Salemites were initiated or signed by Putnam and that his daughter cried out on so many people who he either held a grudge against or from whom he wanted something.
Moreover, Giles Corey presents a deposition to the court in Act III indicating that Putnam "coldly prompted [his] daughter to cry witchery upon George Jacobs" so that he could purchase Jacobs' land. Putnam was heard to say that his daughter had "given him a fair gift of land" when she accused Jacobs. In other words, Putnam wanted his political enemies to be convicted of witchcraft out of resentment and ill will, and he seemed to want others convicted out of greed.
He wants them convicted so he can purchase their land. According to the law if you are convicted of witch craft, not only will you be hanged but you will also forfeit your right to your property. The property will then be sold. Putnam is the riches man in Salem and can buy whatever land he wishes once it has been taken from its rightful owners.
Recall that Giles Corey presents a statement that alledges that Putnam has his daugther accuse people who have prime land. Giles tells Danforth, after Putnam's daughter has accused George Jacobs of witchcraft, "If Jacobs hangs for a witch he forfeits up his property - that's law! And there is none but Putnam with the coin to buy so great a piece. This man is killing his neighbor's for their land!"