<2020 “But for now, Modi [[India’s Prime Minister]] is the winner. By going all-in for Trump in a U.S. election year, Modi has guaranteed that the White House will stay silent on critical issues.”—The Week, 6 March, page 15>
<2020 “But the fact the Putin’s hackers went all-in for Trump, who won the electoral college with just 46 percent of the vote, turned a Russian win into a rout.”—The Week, 20 March, page 37>
<2020 “The Fed Goes All In with Unlimited Bond-Buying Plan ¬ The Federal Reserve will buy bonds as needed to calm markets, and will buy corporate debt in a series of emergency lending programs.”—New York Times, 23 March>
The expressions all in or all-in don’t sound right to me. In fact, before I came upon what I took to be the recent onrush of their use (little did I know (>:)), I couldn't recall ever coming across them before.<2020 “Democrats are ALL IN to elect Joe Biden and defeat Trump in November, but we can’t do it alone.”—Add by Democratic Action, democraticgovernors.org., 23 May>
And should it be hyphenated or not? People, for example, as far as I knew, could go all out, or is it all-out, when used as an adverb or give an all out, or is it ‘all-out’ effort when used as an adjective. I probably should know about the hyphenated or not question here but don’t

But as far as the question at hand of using the “in” for my “out” in the above quotes, as far as I can recall, and admittedly my recall hasn’t been improving with age

First, to try to nail down the dictionary definitions and hopefully untangle, at least the grammatical confusion, I consulted Merriam-Webster’s Unabridged Dictionary and The Oxford English Dictionary, but alas, as you will see confusion on some points still remains:
all–out adjective
1) exerting every energy and employing every resource (as military, economic, and political)<an all-out offensive>: thoroughgoing and unreserved<the all-out support of the press><all-out reformers>: without reservation
2) full-blown <an all-out ban>
Origin of all-out: all out
First Known Use: 1893 (sense 1)
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Note: It seemed to me that all-out should also be listed as an adverb, for example, as used in “He went all-out to complete the job on time.” But in the many dictionaries I checked it wasn’t. I finally stumbled upon the answer when I found that when used as an adverb, technically it should not be hyphenated. It should read all out.
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all out adverb:
1) Entirely, completely, totally, [[extremely, awfully]]. Now chiefly Irish English and English regional (northern).
2) In a manner that involves using all one's energy or determination; with full vigor, determination, or enthusiasm or with full use of one's powers, ingenuity, and influence, especially in an effort or a cause, fully, wholeheartedly. Especially in to go all out: to do something as fast or energetically as possible; to put all one's efforts into achieving a specified end; to try one's hardest, to do one's utmost — used chiefly in the phrase go all out<went all out for excess-profits legislation><go all out to complete a job><prevented them from going all out>
First Known Use: 1840
Synonyms: full blast, full tilt
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Note: In checking through many examples, I found that all-out is often used, although technically incorrectly, as the adverb.
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all–in adjective
1) chiefly British : Inclusive of all categories, participants, etc.; from which nothing or nobody is excluded; comprehensive, all-embracing, all-inclusive. <all-in health insurance><an all-in 10-day tour><all-in cost><all-in weight>
2) completely determined : sparing nothing<an all-in effort>
3) of wrestling : without restriction : having almost no holds barred
Origin short for all-inclusive
First Known Use: 1886 (sense 1)
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all in adverb (and interrogative)
1) colloquial. Originally U.S. At the end of, or having used up all of, one's resources (of money, energy, etc.); exhausted, tired out; worn out; done for.
2) In general use: completely committed (sometimes specifically financially) to, or wholeheartedly in favour of something; in a way that shows a lot of determination and a willingness to take a big risk in order to achieve something – frequently with on. <Rather than take the safer path and keep his day job, Merkley went all in and quit his executive post.><Congress and the President have gone all-in to prop up the economy.><It's a comedy drama about two colorful Las Vegas defense attorneys who go all in when it comes to representing their clients.>
3) Poker. Completely committed to a bet, having staked all one's money or chips. Frequently in to go all in. Also as interrogative : a declaration by a player that he or she is making such a commitment.
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So. It appears that the British all-in covers a bit more ground than the U.S. all-out, but they may be used interchangeably in some instances such as was the case in my original quotes above. And note that, technically, since in those first three above quotes it is being used as an adverb, the first two should not have been hyphenated. And as far as hyphenating or not hyphenating both the adjective and adverb of both the ‘out’ and ‘in’ expression, it appears that many folks don’t pay much attention to the dictionary rules. Well I’ll be damned!! (<;)
The following are some quotes provided by the Oxford English Dictionary and some archived sources:
OK. I Admit it! (>:) I must have had my eyes and ears closed to this expression and for some strange reason it just never registered! I started writing this posting in early March and then laid it aside until today. Since I put it aside I have heard and read more all-ins than I can handle.<1840 “There was those . . . as thought that he'd have gone all out for a soldier, but for the mother and sisters.”—Fraser's Magazine for Town and Country, October, page 434/1>
<1908 “Ain't she a likely filly... If there's anybody that could make me good, it's her. I'm all in.”–Round-up by J. Murray & M. Miller, viii. page 144>
<1908 “The ‘all-in’ system—that is to say, railway and hotel accommodation combined.”—The Westminster Gazette, 6 June, page 9/3>
<1933 “It was becoming impossible to retain self-respect, to be happy within oneself, unless one was ‘all in’ upon that one sound objective.”—Shape of things to come by H. G. wells, III.§1. page 263>
<1965 “He denied a statement he made at the week end would prejudice the success of the all-in conference on the waterfront.”—The Age (Melbourne, Victoria, Australia), 27 October, page 6>
<2005 “The more I thought about my all-in strategy, the more I didn't like it.”—Moneymaker by C. Moneymaker & D. Paisner (2006), vii. page 165>
<2006 “Girls, cut the guy a break. He's trying so hard, he's gone all out to please.”—Touch, December, page 74>
<2013 “‘All In with Chris Hayes’ will premiere on April 1st at 8 p.m. ET on MSNBC.”—webcitation.org, 22 March> [[When they name a TV show using the adverb, I begin to wonder where I have been all these years. (>:)]]
<2015 “In just the past year, President Obama has been said to have been all in on free trade, climate change, and criminal-justice reform.”— The New Yorker, 7 September>
<2020 “‘I offer myself as a doer and a problem solver -- not a talker. And as someone who is ready to take on the tough fights – and win,’ Bloomberg said in a statement on his website. ‘Defeating Trump -- and rebuilding America -- is the most urgent and important fight of our lives. And I’m going all in.”—abcnews.go.com, 19 March>
<2020 “Philanthropy: A tech chief goes all-in: Twitter CEO Jack Dorsey pledged to donate $1 billion of his wealth this week to coronavirus relief programs . . .”—The Week, 17 April, page 30>

Note: For an interesting article on this subject see this New Yorker Going All In on “All In” , which was written, I wouldn’t have believed it, in 2015 !!!
This all goes to demonstrate that nobody’s perfect, although I’ve often come close. Not!!! (<:)
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Ken Greenwald – May 27, 2020