jeez, where to start??
First, the NFL doesn't "participate in sports betting" (anymore than they are participating in the manufacture of pickup trucks or beer)..betting companies are sponsors no doubt paying huge fee for the partnership.
Second, the ALL pro sports are simply entertainment and nothing else. Differentiating between "sport" and "entertainment" is a meaningless exercise. A casino, by definition, is a place of entertainment (literally, filled with "games" one can play)---and obviously legal betting happens there.
Third, Congress has no interest in reigning in the NFL--try campaigning on that.