Why does Iago hate Othello?

The main reason Iago gives for plotting to destroy Othello is a suspicion that Othello may have had an affair with Emilia. However, Iago himself admits that he doesn’t know whether these rumors are true or not, explaining that “I know not if’t be true / But I, for mere suspicion in that kind / Will do as if for surety” (1.3.). Iago also mentions that he is attracted to Desdemona himself: “I do love her too” (2.1.). Neither of these reasons seem totally sufficient for just how much Iago hates Othello, and notably, he declines to answer when Othello asks him his motivation at the end of the play, saying only “Demand me nothing. What you know, you know” (5.2.). The lack of clear reason for Iago’s destructive hatred is part of what makes him such a chilling and effective villain, since in part he seems to take pleasure in destruction for destruction’s sake.