prey on

Plunder or pillage; also, make a profit at someone else's expense, victimize. For example, Vikings preyed on the coastal towns of England, or The rich have been preying on the poor for centuries. [Late 1500s]

Hunt, especially in order to eat, as in Their cat preys on all the rodents in the neighborhood. [c. 1600]

Exert a baneful or injurious effect, as in Guilt preyed on his mind. [c. 1700]