It’s their best choice right now. If B1G/pac/acc wanted the other players they’d have taken them long ago.
PAC teams are already whining about not getting enough money for their liking. They’re sure as heck not going to increase their per team payout by simultaneously
A- splitting the pie with another mouth or two to feed. (TCU is not going to bring in more than it’ll consume…Less money per team)
B- increase expenses (travel, etc)