Accountants
Attorneys
Business Model Analysts
Tax Experts
Members of Congress

And ALL those people are the reason the NCAA still exists. The recent SCOTUS ruling has zero financial affect on the NCAA. Member institutions still pay their fees. The NCAA still has considerable authority, be it as I have long argued, limited because it's association bylaws do not trump state legislatures or congress.

But, the NCAA member institutions are competing as quasi professional entertainment sports franchises against one another and that makes them businesses. As businesses they are exempt from a ton of special conditions and policies, laws and regulations that PROFESSIONAL SPORTS ENTERTAINMENT LEAGUES (NBA, MLS, MLB, NFL, NHL, etc.) must all comply thereto.

Biggest reason they stay in the NCAA is that if they leave, they become direct business competitors to those pro sports leagues. They already are, but the NCAA shields them and their revenue from a lot of the competitive equalizers. When Michigan sells a baseball cap, the funds go to the University and disappear. When the Detroit Lion sell a cap, the money goes through the state and federal tax corporate income tax filter. Trust me, the Lions, Red Wings, Pistons, etc. across the board are NOT going to just sit back and let UM, MSU etc. compete with them for concession dollars, ticket revenue and TV revenue on a non-equal tax basis.

The reason the P5 leagues have NOT bolted the NCAA is because it protects them from professional sports business realities.