Bush was arrogant.
Gore, on the other hand pulled an all nighter campaigning in the only state where he outspent Bush, Florida. Gore said that Florida would come down to 1 vote per precinct. Of course, even that estimate was too high.
If Gore had asked Clinton to campaign in FL for the last several days, attacked Bush Jr. on his DUI story much more severely, and consistenly asked people if they were better off than there were eight years ago right before the election, Gore would ahve probably won Florida by several thousand (not hundred) votes, if not more.
I'm sure that some seemingly completely irrelevant things could have swung the necessary 0.004% people to vote differently (0.0015% for Gore to have led in the recount).
