I've basically been on bed rest for the past 3 weeks. I had never watched Breaking Bad until then. Netflix and Google got me caught up quickly. What a show.
Vince Gilligan is on record several times about how he wanted a show where the main character goes from Mr. Chips to Scarface. I think that's an apt description of Walter's progress. The writing on this show is fabulous. As is the acting. As is the cinematography. Hard to find one weak side.
Saying that WW isn't 3D is not a knock on anything about the show. It's just an observation. Many have tried to pinpoint the exact moment that Walt turns, but I think that moment is impossible to find because from Pilot, Walt is a narcissist. THAT is his fatal flaw and it's present in him from before his 50th birthday. What changed from Pilot to Felina wasn't Walt, it was the situations into which Walt was placed. Yikes -- that passive voice really makes it sound like Walt has no agency. The 7 writers of the show would not approve. But I digress.
In saying that Walt does everything for his family, that is true -- but only to him. His actions are selfish through and through. The old (and lame) saying that there is no selfless act because it makes the one doing it feel good afterwards does not hold true as a generalization, but it DOES hold true for Walt. Every seemingly selfless act Walt does has an ulterior motive underlying it.
For instance, Walt is neither in the meth business or the money business. At the same time, however, he is not in the empire business either. He is in the business of making the best meth anyone has ever seen. When he tries to leave the business, his motivation for re-entering is never about money OR meth -- but about the pride he gains from cooking.
Any time he finds himself in a bind, he is able to project the blame onto another character (often Jesse -- that poor sonofagun). When Walt breaks the norms of proper behavior, he feels entitled to do it. Those norms, after all, are for everyone else. He is different though.
These are all classic symptoms of narcissistic personality disorder. I believe THAT diagnosis even has primacy over his sociopathy. He is first and foremost a narcissist. And that started at the beginning and continues to the . . . well at least through the penultimate episode. We shall see.
BREAKING EDIT: The above was confirmed in the series finale "Felina." "I did it for me. I liked it. I was good at it. I was alive."