the combination of all of them that has led to this. Honestly, I think USC's mediocrity has a role to play. If they had been dominating the PAC12 and going to national championships I think it is a lot less likey they look somewhere else. The PAC12 money would have been better in that scenario anyway.
In some respects the same is true with Texas. Their mediocrity caused the Big12 to not be as good as it should have been. But their leadership didn't screw up as bad at PAC12 leadership did...over and over again.