I have trouble defining an artist.
Beethoven, Mozart, and many others supplied music for their sponsors. Music they did for their fans, at the request of their fans, and targeted to the taste of their fans and wrote some pretty artistic music that has lasted for a long time.
Cole Porter and the Gershwin brothers wrote some pretty artistic commercial music for Broadway Plays, as did Harold Arlen and so many more.
Michelangelo did not want to paint the ceiling of the Sistine Chapel, he wanted to do a sculpture of I think a horse. The pope at the time basically forced him to paint the chapel. It turned out to be one of that century's greatest works of art.
Throughout history, great artists have done commercial works for patrons, sponsors, targeted audiences or whoever else and have still managed to create great works of art that will last longer than their lives.
So I think all the things previously mentioned CAN apply to an artist, but are not necessarily requirements.
I think the only requirement of an artist is that his or her work is artful.
And what is artful? What is art? That's another subject.
I for one think Jackson Pollock's drop cloths are not great art but simply messy kitsch, but there are 'experts' who strongly disagree with me.
Insights and incites by Notes