I am sure it is a lot of money...and it is a nice place to live (especially compared to Manhattan, KS). Heck, Calhoun seriuosly considered leaving UConn to go to South Carolina when they backed the Brinks truck up for him many years ago.
I was thinking it's likely all about money and a little about location. As for which program it is easy to recruit for and win, KSU seems to have a heck of a lot better track record. When was the last time USC-east was a relevant hoops program? Frankly, I can't remember.
Like JC, FM is one tough SOB who knows how to recruit and get the most out of his players. Doing what he's done in Manhattan, KS in SC will be a tall order when most of the top South East kids usually end up at UNC, Dook, UF, UK, WF, GT, and I'm sure a few others before they think, "Oh, I gotta go to U of South Carolina! That's the place to go!"
Then again, he did find a way to get good players to come to Manhattan, KS, when big time programs like KU, UT, and some pretty good hoops programs like Mizzu, Baylor, etc. are in the general but vast geographical area.