people don't seem to be realising that villain has only 1/2P left in his stack. we need >50% equity against the range he calls our river bet with in order for betting to be +EV. this may be giving him too much credit because he's a 77/5 but the following range gives him all straights, sets, two pairs, and a decent amount of Qx (i believe he definitely has as low as Q6s+ in his range here because he's a 77/5 and it's a suited picture card)

Board: 9s Qd 7c 3c Ks
Dead:
equity win tie pots won pots tied
Hand 0: 37.662% 33.77% 03.90% 26 3.00 { AsQs }
Hand 1: 62.338% 58.44% 03.90% 45 3.00 { QQ, 99, 77, AQs, KQs, Q6s+, JTs, 97s, AQo, KQo, Q8o+, JTo, 97o }

based on this range, a king is basically the only river card we can't jam for value - it kills some of our action from 9x hands, and any draws he may have had either missed and aren't calling (T8), rivered the nuts (TJ), or rivered a pair better than ours and are calling (if he has KT or KJ in his range), so unless he's calling with 9x, TT or JJ on this river, the Qx combos we beat are outweighed by the >two pair hands.