IBM is trying to prove that computers can & will become smarter than humans.
I wouldn't exactly say that, because as we proved with the U.S. Cities question, in which we have learned that Quebec is now a major U.S. city. Honestly, IBM did this to prove that computers could, at one point, think like humans. Technically, Watson just knew what any other Jeopardy contestant would know, it is just that Watson could press the button faster. The average human takes about 0.3 seconds to react to something, whereas Watson could take only 0.03 seconds, depending on how far away Watson is from the room playing Jeopardy.
There is one thing that Watson could never understand that humans can, and that would be emotion. No sort of artificial intelligence can understand human emotion or learn the way we do. Watson technically was only force-learned how to recognize letters, then given a bunch of books and articles to look over and try to digitize itself, then given over 20 different algorithms to let it decipher human language. Besides, IBM said that what they're going to do with the money is donate it to charities. I mean, that computer cost well over $1 Million (USD), so if they were to keep the money for themselves, it wouldn't fill much of the gap.