He has an asset worth $1B, returning 6.1% interest. I'm not crying for the guy, but it certainly is on par with what he could get if he invested $1B elsewhere.
The value of the NFL franchises has risen dramatically in recent decades (they paid just over $200M in 1993, now it is worth over a billion)
One of the arguments about why pro sports are good investments is NOT necessarily about the money returned each year (although 6% annual return today would be fine for 2010-2012 if your calculated value of a billion paid were to be correct) but that the franchises have been escalating dramatically in overall value. (So any owner unhappy with a "6%" return investment with public support should feel free to sell out a reap another giant windfall).
They have been lying about losing money
They have been receiving public money for their stadium etc.