Wade's motives

Watched this movie on channel Film 4 last night here in the UK and quite enjoyed it. While I personally didn't think it was a great film, I thought it was, nonetheless, above mediocre, well made, gritty, realistic and entertaining; as others have highlighted, all the acting performances were strong, particularly those of Cage and Poulter. (Incidentally, I've just read there that the guy Poulter -- who played Wade -- was literally a homeless drunk, albeit one who was smart and bright, with an interesting past, and who actually had aspirations of becoming an actor after dabbling with the industry in his early years. Remarkable and intriguingly serendipitious. Will need to read more on Poulter's real life.)

Anyway, to the subject at hand . . . I think Wade's actions and motives were a combination of what previous posters have said: he knew it was morally wrong, he empathised slightly with the drunk black man, as he was kinda a reflection of Wade and Wade knew this, but expediency was the stronger force within him; criminality took over in order to support his addiction and alcoholic lifestyle. Also, as another poster has already indicated, the nomadic alcoholic lifestyle he was living had rendered him mentally ill, perhaps to the point of being psychotic; essentially, the scene, imo, represents the presence of traits with contrasting duality that were within him: empathy and psychopathy.