Fox didn't destroy the pac 12. He just didn't see value there. ESPN didn't destroy them either, in fact, they offered them a $30 million deal. Arguably, Apple destroyed them by offering a lowball deal when they knew they were the only better in town, but even that is a reach. Now there's a fairly decent argument that the Big Ten destroyed the pack because it raided it twice and the second round was the straw that broke the camels back. We know, in fact, that had Washington and Oregon not left, the GOR was going to be signed in the conference would've stayed together, oh and we would've been added to the big 12.
No, it was the Pac 12 leadership that destroyed the Pac 12. They should have taken that $30 million deal from ESPN. Once they didn't, their fate was sealed.