Daisy is ready to use and abuse everyone that meets her and anyone that she can.  In some ways she is even a victim of her own disconnection from reality.  Likely one of the first people she victimizes, in a way, is her husband Tom, but that is a two way street since he is cheating on her at every opportunity.  Since their relationship is a bust, she just uses him for the position and power his money provides, as well as the general illusion she has about money making everything ok.

The greatest victim (though also a victim of his own illusion) she preys on is Gatsby himself whom she leads on only to destroy him when she realizes that he could be the vehicle for saving her from her murder (or manslaughter).  He is destroyed and despite that fact continues to long for her.