Abstainer

noun

A weak person who yields to the temptation of denying himself a pleasure. A total abstainer is one who abstains from everything but abstention, and especially from inactivity in the affairs of others.

    Said a man to a crapulent youth: "I thought
    You a total abstainer, my son."
    "So I am, so I am," said the scrapgrace caught --
    "But not, sir, a bigoted one."

        G.J.


—Ambrose Bierce, The Devil's Dictionary