They may not make as much as the B10 is making in the next couple of years, but they make more from the CFP and their bowl games. 3) Although they haven't been incredible on a national level for years – until this year – their independence stands out as a better-than-thou school. 4) They are popular and will get picked for CFP if they are near the top, 5) They control their schedule and have been able to play 8 home games (plus a couple neutral site games).
For most schools the conference is good for getting a schedule in October and November. Conference teams get guaranteed media $$ (some get more and some get less). Your conference stands up for you and your peers (voting block). ND doesn't have an issue with any of this.