Post-season access to the playoff, the NY6 and the top other 13 bowls is only part of it.
They have autonomy to draft their own legislation without interference. Each January, during the annual NCAA conference, those 65 schools meet, privately, to discuss and/or adopt measures that benefit them, without any thought about how those measures might affect the rest of FBS, or others schools in Division 1.
You are right when you say it isn’t about money.This is about power. That’s why they are called power conferences. They will never share that power with anyone else. It’s an exclusive fraternity - outsiders need not apply.