Jagger was one of the most famous pop musicians of the day, and Andy Warhol has a reputation for being a freak. He never comes across as a very inaccessible guy.

Formality's best unlearned at as young an age as possible.

Jagger is also unusual among musicians in that he has an excellent grasp of business (including obviously the business of making popular music). Others might include Madonna, Sting... whatever you think of their music, those artists and a few others have done much better than the average rock star at maintaining control over their work and financial sanity.

another example is ZZ-Top.

Jagger was also one of America's top artists at the time.