That is probably a false statement, but we don't know the numbers, so no point in arguing it.
The only team in the NFL where the profit is known is Green Bay due to their status as a non-profit corporation.
If you are interest to see what the financials look like for a NFL team, albeit the most unusual team from a ownership/financial perspective, there are a lot of details
in this article here.
Their operating profit was $14m on revenue of $375m.
$226 million of their revenue came from NFL revenue sharing. All teams received an equal amount.
$149 million of their revenue was 'local' review generated from their pro-shop and other team owned avenues that don't fall under NFL revenue sharing
Additionally, the Packers sit on a war-chest of $280 million (ie their reserve) which increases just about every year since they really have no place to spend it given the fact they have no owner taking money off the top, the already have top notch facilities (both practice and stadium), etc.
Considering how much more revenue the Cowboys make per year, its easy to understand how Jerry Jones's net worth continues to climb.
Unfortunately, under the NFL Salary Cap, this cash advantage really provides the Cowboys no real practical advantage.