be one's own worst enemy

• (Received Pronunciation) IPA^(key): /biː wʌnz‿ˌəʊn wɜːst‿ˈɛnɪmi/
• (General American) IPA^(key): /bi wʌnz‿ˌoʊn wɜɹst‿ˈɛnəmi/

• Audio (General American):

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• Audio (General Australian):

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• Hyphenation: be one’s own worst en‧e‧my

be one's own worst enemy (irregular; see the conjugation of be)

1. (intransitive, idiomatic) To act contrary to one's own interests; to cause problems for oneself; to self-sabotage.
   • 1861 March 29, “Reply of Rev. Mr. Haven”, in W[illia]m Lloyd Garrison, editor, The Liberator, volume XXXI, number 13 (number 1580 overall), Boston, Mass.: J[ames] B[rown] Yerrinton & Son, printers, →ISSN, →OCLC, page 51, column 3:

     [Mr. Haven] objects to our making the Liberator a free, impartial, independent journal, allowing all sides to be fairly heard (as we invariably do) in its columns. He insists on making it (what it has never been) the official organ of the Anti-Slavery Society; […] The American Anti-Slavery Society has an official organ,— […] that paper scrupulously adheres to its one object, excluding from its columns the discussion of those subjects which are so distasteful to Mr. Haven in the Liberator. That paper, therefore, cannot justly be charged with "being its own worst enemy."

   • 1870, Mary Dwinell Chellis, chapter I, in Mark Dunning’s Enemy (Standard Series of Temperance Tales; III), Boston, Mass.: Henry A. Young & Co. […], →OCLC, page 27:

     "We won't talk of that now," answered Mrs. Forbes. "Mark is his own worst enemy. Good night." True. No enemy however powerful and malicious, can so work a man's ruin as his own unbridled passions and depraved appetites.

   • 1881, Ogier Ghiselin de Busbecq, “Letter III”, in Charles Thornton Forster, F. H. Blackburne Daniell, transl., The Life and Letters of Ogier Ghiselin de Busbecq, Seigneur of Bousbecque, Knight, Imperial Ambassador […], volume I, London: C[harles] Kegan Paul & Co., […], →OCLC, page 221:

     For each man is his own worst enemy, and has no foe more deadly than his own intemperance, which is sure to kill him, if the enemy be not quick.

     Originally written in Latin on 1 June 1560 (Julian calendar) by Busbecq and published in his Turcicae epistolae (Turkish Letters, 1595).

   • 1898, Horatio Alger, Jr., “Bought Off”, in The Young Bank Messenger, New York, N.Y.: Henry T. Coates & Co., →OCLC, page 229:

     He had been his own worst enemy. Once a prosperous lawyer, he had succumbed to the love of drink, and gradually lost his clients and his position.

   • 1922 March 4, Harry Leon Wilson, “Merton of the Movies. Chapter VII: ‘Nothing To-day, Dear!’”, in George Horace Lorimer, editor, The Saturday Evening Post, volume 194, number 36, Philadelphia, Pa.; London: Curtis Publishing Company, →ISSN, →OCLC, page 19, column 2:

     So far as he could see, the girl had no screen future, though doubtless she was her own worst enemy. If someone had only taught her to be serious her career might have been worth while.

   • 2021, Henry C. Duggan, III, “Track Firestarters”, in Savannah on Fire, 1820, [United States]: Amazon Books, →ISBN, page 125:

     The Spanish arsonists have fled. […] But they are so blustery about their plans, they are their own worst enemy. Let's obtain two horses and then go into pursuit.

   • 2024 April 20, Phil McNulty, “Manchester City 1 – 0 Chelsea: Bernardo Silva Scores Late Winner as Holders Reach FA Cup Final”, in BBC Sport‎^[1], archived from the original on 5 October 2024:

     [Mauricio] Pochettino set his team up ideally to keep City at bay but once again, as they did in that Carabao Cup final loss to Liverpool, Chelsea were their own worst enemies as they squandered opportunities to banish memories of that reverse.

• “be one’s own worst enemy, phrase” under “enemy, n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “be your own worst enemy”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.
• “be your own worst enemy” in Longman Dictionary of Contemporary English, Longman.
• “be your own worst enemy” (US) / “be your own worst enemy” (UK) in Macmillan English Dictionary.