The final chapters of The Beautiful and Damned are full of tragic situational irony. The main source of irony is that when the couple finds out about the inheritance, Anthony has already become too depressed and alcoholic to fully appreciate it. In Chapter 9, the story unfolds from the perspectives of two people who see Anthony alone on the deck of a boat. The two men speculate about his appearance and state of mind:
“That’s him,” he said, pointing to a bundled figure seated in a wheel chair near the rail. “That’s Anthony Patch. First time he’s been on deck.”
“Oh—that’s him?”
“Yes. He’s been a little crazy, they say, ever since he got his money, four or five months ago. You see, the other fellow, Shuttleworth, the religious fellow, the one that didn’t get the money, he locked himself up in a room in a hotel and shot himself——”
This passage demonstrates the ironic disparity between Anthony's so-called victory ("he got his money") and his state of mind ("crazy"). When he finds out about the inheritance, he is sitting on the bathroom floor clutching his stamp collection, a powerful image that underscores his childishness. He has learned nothing from his mistakes and remains incompetent, greedy, and useless. The irony here is that despite having satisfied his initial desire for the inheritance, he is so physically and psychologically messed up that he cannot take much joy in its value – nor can it return him to his original, optimistic, youthful self. He claims to have succeeded in "a hard fight," but he lacks the clarity of mind to make use of the fortune and will likely squander it in the same way he wasted his old money on apartments and alcohol. He sits in a wheelchair, fighting to maintain his delusional view of himself.
In the passage above, a shift in perspective heightens the irony of the scene. The reader likely expects the end of a long novel to center on its protagonist's development, but here the narrator fills the page with the speculations of two random men. Among New York society at large, Anthony has become well-known as an unstable person whose mind and body have deteriorated under the effects of alcohol. The two men represent the opinions and speculations of society; their names remain unknown, but their opinions have prominence over Anthony's perspective in this scene.