Walt didn't lose his morals, though, he just lost his pretense that he had them in the first place. It was never about paying his bills/providing for his family once he's gone or all the other justifications he kept making for himself, it was about his pride, as is evident by his turning down a huge load of money in episode 2 and him admitting to it i' the second-to-last (or near that, I'm not sure) episode.