Súil le cúiteamh a mhilleas an cearrbhach.
Hope to recoup is what ruins the card player (gambler).

From The Poker Encyclopedia:

"All veteran and professional poker players know that peculiar tug of desperate greed which lures the luckless deeper into the trenches of loss. It's when this sense of futility sets in that the chemistry of luck loses its winning edge completely, and further play can only result in more dire losses and the sure extermination of one's bankroll. This point of no return is captured in the old proverb, 'Hope to recoup is what ruins the card player,' from the Mhilleas Cearrbhach novel, Hope to Recoup. Happy are the veteran players who find a novice at their table who does not know when he has reached this precipice of loss."