Define "winning big".
Gary's first year as HC at TCU was in 2001, his 2002 team won 10 games, a conference title, and finished in the top 25 for the first time in roughly two decades.
2005 they won 11 games, beat #5 OU in Norman, and finished in the top 10.
2008-10 they won 10 or more each year, won the conference three years in a row, won the Rose Bowl, and finished in the top 10 all three years with a high of #4 in 2010.
Somewhere between 2001 and 2010 there was an extension as Gary was considering other jobs, but again what do you consider winning big.
One other point that I think gets lost with Gary and why he stayed a TCU so long is that he coached at TCU through 4 conferences (3 as a head coach) so while he was at the same school the challenges to his program did change as the the competition increased with each new conference.
I think that is important because coaches don't simply jump for money, it helps, especially if they throw stupid money at you like ATM and Jimbo, but I do think some of these guys in the words of Reese Bobby, start to get a bit itchy when things are just a bit too perfect.