Final answer:
Stephen Foster's primary source of revenue was music compositions, though he eventually faced financial hardships and died with very little money.
Step-by-step explanation:
Stephen Foster, known as America's original pop star, primarily made his revenue from music compositions. Foster skillfully combined African and European musical traditions to create beloved hits like "Oh Sussana," "Nellie Bly," "Camptown Races," "Old Folks at Home," and others. Despite his initial success and the lasting impact of his music, Foster endured financial difficulties and tragically died with little money to his name.