Why does the narrator give up his musical ambitions in favor of making money in The Autobiography of an Ex-Coloured Man?

The narrator's musical ambitions are connected very strongly to his "blackness"; he wants to find a way to merge ragtime -- an African-American musical form-- with European classical music. 

The problem is that he is tempted to take advantage of his light skin color and try to "pass" as a white man.  This would have been a temptation to any African-American of light skin color in those times of open racism. 

     The narrator makes his decision after he witnesses the lynching of a black man (see link below).  Instead of causing him to hate whites, this incident produces in him a terrible shame and embarrassment about being black; he becomes ashamed of "being identified with a people that could with impunity be treated worse than animals."

      He begins to pass himself off as a white businessman, and soon becomes quite successful.  His fate is sealed when he meets and falls in love with a beautiful white woman.  Although he eventually admits to her his origins, he cannot marry her, and live with her the life that he wishes to, if he reveals his origins to anyone else.