But Sean Dailey points out in a fine piece that it's not as simple as it appears:
Such an analysis may strike fans of the movie as a bit off, given that, on a certain level, it is a cornball movie. It’s a Wonderful Life has corny dialogue, corny humor, slapstick, hijinks and low-jinks. But beneath all that, it also is a very dark film. Opening with George’s friends praying that he can be found before he does the unthinkable, death hangs over it, and each death, even the deaths George prevents, sends him in directions he does not want to go, pulling him further and further from his dreams and ambitions, turning him into every bit the “warped, frustrated young man” that Mr. Potter says he is.
Read it all.