He really wanted to be King of New York

According to the NYTimes, Michael Bloomberg $102 million to be (closely) reelected as Mayor of New York City (making $264 million to win all three elections. $261 million of which came right out of his own pocket.)

Certainly he has the money to do this, but wow.

For a baseline, the most expensive Senate race in history (Coleman-Franken believe it or not) cost $50+ million between both candidates.