I think it's pretty well known that Patterson is apparently not a good interview for ADs. But with his winning, that alone can't be the reason he is still at TCU, so it must be part him, part ADs not finding him "attractive" during an interview.
I would have to go with the latter being the biggest reason. Of course he wouldn't go from TCU to Memphis, but in the last 6 years or so, think of all the programs that have been in a coaching search...
Texas A&M, Oklahoma State, Clemson, Georgia Tech, LSU, South Carolina, Tennessee, Auburn, Ole Miss, Mississippi State, Miami, North Carolina, NC State, Kansas State (twice), Colorado, Baylor, Florida, UCLA, Stanford, Arizona State, Louisville, West Virginia, Michigan, Michigan State, Northwestern, Indiana, Illinois, Arkansas, Arizona, etc.
And those are just the ones I can come up with in my head going through each conference. It is just odd that not one of those listed, and the majority of those listed are upgrades from TCU, were never the right fit....for whatever reason.
Who knows, maybe he just wants to stay there and continue to build it over the next 20 years. Like EA said, he has to be pretty comfortable, winning 10+ five of the last seven years (about to be 6 of 8) will do that.