I think you might be confusing BTN payments with total payments for all rights packages. The BTN isn't as wildly profitable as people think it is. It distributed about $1 million to each school in 2014-15. http://www.jconline.com/story/mike-carmin/2015/07/16/btn-profits-increase-big-ten-revenue/30226149/ The lion's share of the projected TV payments will come from the T1/T2 Fox and ESPN deals.
Like the BTN, the LHN is a Tier 3 rights package, so ESPN is basically paying UT $15 million per year to televise its 2 worst games. That's a guaranteed payment regardless of profitability and ESPN covers 100% of the production costs. It's the best T3 rights deal in the nation. For comparison, NBC pays Notre Dame $15 million annually for all their games. UT also gets ~$24 million for their T1/T2 rights as part of the Big 12's TV deals, so their take is closer to $40 million.
That said, I agree with you that even $15 million per year isn't worth blowing up a conference, and Texas couldn't even touch Big Ten TV money as an independent.
I need to see all these payouts in a graphical format. I'm a visual learner.