Not that successful, assuming you're talking about American football. The players as a whole get a bit less than half of all revenue coming in despite being the ones to actually, you know, play the game.
That sounds a lot more successful than most other industries. I don't think software engineers, or retail employees are getting half of the business' revenue. That sounds like a pro union example.
Well, they (and the others) should be getting even less. States or cities subsidizing stadiums isn't as beneficial as originally thought. Those making obscene amounts of money from a public resource should probably contribute more to the infrastructure required to make that money.