One river decision with the best hand you could possibly hold that still loses to everything worth betting. The cards stop mattering the moment you can name the shape of the spot — after that it is arithmetic.
Hand info
Heads-up, single raised pot, no ante. Blinds 0.5 / 1.
RIVER · 40BB EFFECTIVE
RIVER · BB CHECKS · BTN BETS 10BB
2-max table. Hero is BB with 40 big blinds effective. RIVER: 9s, 6s, 2h, Ks, 4s. RIVER · BB CHECKS · BTN BETS 10BB. Hero holds Kh and Kd.
Hand history
Pre-flop
Flop
Turn
River
You turned a set of kings and check-called again. The river is the 4♠ — a fourth spade. Your hand did not change; the situation did. On 9♠6♠2♥K♠4♠ there is no pair on the board, no straight available and the last king is the board’s own K♠, so your set beats every hand in the deck that does not contain a spade — and loses to every hand that does. The button bets 10bb into 20bb.