mug's game

idiomatic

(idiomatic) A foolish, profitless, or hopeless undertaking.

Japanese Meaning

愚かで利益の得られない無益な試み / 無駄な努力・徒労な行為

Chasing the lottery jackpot after months of losses is a mug's game.

何ヶ月も損を出した後に宝くじの大当たりを追い求めるのは、割に合わない愚かな試みだ。

Sense（1）

(idiomatic) A foolish, profitless, or hopeless undertaking.

‘It's a mug's game,’ said Crabbe.

mugs' games

（ plural ）