Most of the really big soccer clubs in Europe are owned by the fans or billionaires who wouldn’t sell their teams for double or triple the price listed as the value; and there would be plenty of buyers.
It’s not about the money for any of them, with a few exceptions. Those clubs not owned by the fans are often owned by very wealthy oil Sheikhs who bought them for their personal egos.
You will also see “The Emirates” airlines on the shirts of a number of top clubs. That generates huge ad revenue along with the ads on the video screens bordering the pitches on all sides.
Do not be surprised if U.S. major league sports start having corporate logos on uniforms in the not too distant future. The revenue potential is just too lucrative too ignore.
I saw the Boston Celtics had a GE logo on their uniforms. I never heard any announcements of sponsorship, but the logo is obviously part of some deal with GE and the Celtics.