This isn't because broadcast "can't afford" sports. It's because they've learned that moving this amount of sports away from OTA makes them more money.
ABC/ESPN/ESPN2/ESPNU/SECN/ACCN are all the same company, all under the Disney umbrella. Bally is what used to be FSN, which was temporarily owned by Disney as well after their acquisition of Fox, but Disney was ordered to divest itself of FSN, so they're now owned by Sinclair. As well, Fox's broadcasting properties were spun off into their own company right before the acquisition, including BTN.
There are basically four major sports juggernauts in the US right now. ABC/ESPN, NBC, CBS, and Fox (which for obvious reasons Disney was not allowed to operate after the merger). Notice how that does cover all the broadcast networks. The lack of sports on broadcast television is not because they "can't afford" to license it.
Big events are only on broadcast because there would be riots if, say people couldn't watch the Super Bowl without paying a subscription fee. I remember when Disney moved MNF to ESPN, quite a few people complained.