How To Make Money Musician

How can a person make a lot of money if he is very, very famous but not an actor, musician, or a sportsman ?

Basically I know someone who became quite famous but still unknown by the general public. Is there a way for him to generate additional income if he is not an actor, a musician, a singer, or a sportsman ?

Song writer(composer)
make up artist
director
screen writer
script writer

anything in the back ground

Lil Wayne – Got Money ft. T-Pain