mug's game

plural mugs' games

1. idiomaticA foolish, profitless, or hopeless undertaking.

   ‘It's a mug's game,’ said Crabbe.

   1956, Anthony Burgess, Time for a Tiger (The Malayan Trilogy), published 1972, page 109

   2 more examples

   The sheer destructiveness of nuclear weapons makes the quest for defenses a mug's game.

   1988 May 20, Strobe Talbot, “Inside Moves”, in Time

   Although they aspired, like all natural-born gamblers, to taking a flutter and beating that system (they all loved the idea of tips, of course), they were sufficiently cynical to know it's a mug's game and that it was largely bound to fail.

   2012, David Stevenson, FT Guide to Exchange Traded Funds and Index Funds