Again, his greatest works, the ones we remember, were not done for profit. He was paid for a fraction of what his work was worth.
I never said that artists didn't seek to make money by their art: I pointed out the truism that no truly great work of art (like the Sistina) was undertaken for profit.
Before Michelangelo even touched brush to plaster, he knew he was being underpaid. That apparently did nothing to deter him.