A dictionary of Proverbs (Oxford Paperback Reference)

You cannot LOSE what you never had
The sentiment is expressed in a number of ways: quot. 1974 represents a local equivalent. Similar to what you’ve never HAD you never miss.

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  a 1593 MARLOWE Hero & Leander I. 276 Of that which hath no being do not boast, Things that are not at all are never lost. 1676 I. WALTON Compleat Anger (ed. 5) I.V. ‘He has broke all; there’s half a line and a good hook lost.’ ‘I [Aye] and a good Trout too.’ ‘Nay, the Trout is not lost, for.. no man can lose what he never had.’ 1788 WESLEY Works (1872) VII. 41 He only seemeth to have this. .. No man can lose what he never had. 1935 Oxford Dict. English Proverbs 601 You cannot lose what you never had. 1974 ‘J. HERRIOT’ Vet in Harness viii. ‘Only them as has them can lose them,’ she said firmly, her head tilted as always. I had heard that said many times and they were brave Yorkshire words. "winners and losers
  

lose see also a BLEATING sheep loses a bite; LEND your money and lose your friend; the SUN loses nothing by shining into a puddle; a TALE never loses in the telling; USE it or lose it; you WIN a few, you lose a few.
loser see FINDERS keepers (losers weepers).
One man’s LOSS is another man’s gain

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  с 1527 T. BERTHELET tr. Erasmus ’ Sayings of Wise Men D1V Lyghtly whan one wynneth, an other loseth. 1733 J. BARBER in Correspondence of Swift (1965) IV. 189 Your loss will be our gain, as the proverb says. 1821 SCOTT Pirate I. vi. Doubtless one man’s loss is another man’s gain. 1918 D. H. LAWRENCE Letter 21 Feb. (1962) I. 544 I am glad to have the money from your hand. But..one man’s gain is another man’s loss. 1979 R. LITTELL Debriefing vi. Well, their loss is my gain! "gains and losses