In the "marketplace" of education, the paper was the token that the student expended the mental effort of doing the work, which would be graded on its merits as

In the "marketplace" of education, the paper was the token that the student expended the mental effort of doing the work, which would be graded on its merits as a sign of what he should have done. You faked that token knowingly. Your customer did no work, and the professor would never have accepted the monetary equivalent of what he paid you for that work. Not at any multiple, if he wanted to keep his job and the university its accreditation.