While she’s the only one with a level head in the family, the Countess Rostova is a drag. She could have let Denisov down a bit easier in tone, but it parallels her son’s flippant attitude to losing 43k rubles. She is always “in character” and he, too tries to be someone he’s not which is why he’s having such bad luck in life. Tolstoy is affirming us to “be ourselves”, even if it still fails, like Denisov.
Though I should say that Denisov puts on an act too, he’s not as confident as he acts (that lisp of his) and so he over compensates. But like Nioklai, he too is young and trying to figure it all out. That’s why Dolokhov has been successful up to this point because he knows who he is, what he is, and is realistic about getting what he wants. That’s why the encounter with Pierre was a shock to him since he had never lost before when he really should have won.