Organizations and businesses that survive in chaos (which the college landscape is right now) are organizations that are nimble and can act quickly. When the Big 12 lost Texas and Oklahoma they added 4 new schools within a month.
They also acted quickly to jump the line to secure a TV deal before the PAC.
The PAC (like the Big East before) has been the slow and lost. I don’t see any Big12 teams looking at the PAC leadership and saying they want to be apart of that.