The NFL might distribute money evenly, but only among the select, limited number of teams that the NFL allows to be a part of the NFL brand.
And the way football related is defined is fairly narrow, so some obvious revenue sources (suite upgrades, parking, etc) do not fall under football related and therefore goes to the owners.
Further, the vast majority of wealth the owners make is through the rapidly increasing value of their teams.
At the end of the day the income is peanuts compared to the wealth and asset value appreciation that is generated by the teams.
I think you're looking at this a bit too narrowly - every expense involved in running an NFL team comes out of that 52% that the owners "get", so none of the owners are actually seeing all 52% of that money.
Please note - I'm simply responding to the specifics here - I'm not saying that owners are hard done by, in fact I believe the split should be more weighted to the players (and include roster expansion and more pay/stability for practice squad players).