On the surface, Macomber looks like a well-to-do, groomed sportsman. He is thirty-five years old, wealthy, and knows all about "duck shooting, about fishing, trout, salmon and big-sea, [...] about all court games, about dogs, not much about horses, about hanging on to his money, about most of the other things his world dealt in" (3.17). He enjoys life as a member of the upper crust, for whom leisure time and travel are abundant and money is no object at all. He knows just enough about hunting and absolutely no more. None of the animals he has confronted is "dangerous game," as Wilson calls them.
Even though Macomber's clothes are new, his outlook is naïve, and he's a trembling wreck out in the field, as the narrator describes him: "The fear was still there like a cold, slimy hollow in all the emptiness where once his confidence had been and it made him feel sick" (2.10). Wilson becomes disgusted more by Macomber's whining than by his failure on the field. He even refers to Macomber as a "four letter man" (1.61) – which four letters we'll never know, but it's probably not "dude." All of Macomber's talent at "court games" (you know, squash, handball, and all those oh-so-manly sports) doesn't mean anything to Wilson (or to a lion, for that matter).
Initially, Macomber approaches the safari not unlike the society columnist who gets his references from "Old Simba the lion, the buffalo, Tembo the elephant" (3.18). He wants to go hunting, because that's what men like him do, not because it's what he actually wants to do. Deep down, he is terrified, and definitely does not know what he is in for.
This hapless helplessness is mirrored in his totally dysfunctional relationship with his wife. Before the buffalo hunt, she plainly wears the pants in the relationship, and the most he can muster in response to her badgering is, "'Why not let up on the b****ery just a little, Margot.'" That's hardly the impassioned defense we might expect from a husband whose very manhood has been insulted.
But Macomber undergoes a radical change in the course of the story's few pages. When he kills the buffalo, he becomes a man, finds happiness, and throws off the chains of his harassing wife. Though he has been symbolically associated with prey (running like a rabbit) to his wife's predator, once he kills the buffalo, he starts to take some of the power back.
That is, until he dies at her hand. But hey, at least he dies believing he's on top. At the end, his wife's cheating and his hatred for Wilson no longer matter. He is the scared rabbit no more. Stirred by his success in shooting the buffalo, Macomber goes, in Wilson's words, from being "scared sick" to being "a ruddy fire eater" (4.56) He says himself he feels "absolutely different." (4.10). Maybe we can take that as a small consolation, then; his death comes right as he finds happiness, meaning, and courage.