Sonic's fate

I was just browsing around ESPN this morning and saw this link about the Sonics leaving Seattle. I don't get it. They already have a great venue to play in (went there 2 winters ago and it's in very good condition), great fans, and I'm sure the organization's/affiliates are making some good money from the franchise. So, why is the owner trying to make the city pay for a new arena? Greed, stupidity? I think so. The Key Arena is only 12+ years old and is practically located in the middle of downtown. It's always about money...