I think a lot of people have missed the essence of Walter White.
Walt is legit brilliant, and knows it. Here's the thing. The world doesn't care. And that eats at him, every second of every day. So what does he do? He lies to himself in order to see himself as adequate, as a "good" man. He got finessed out of a company he created, then lowers his expectations of himself to maintain a series of revolving lies.
lie - hes a loving husband and family man, even though none of it is ever enough as his brilliance isn't acknowledged...which is his undying need
lie - his wife is anything but what she is, an entitled shrew who cares nothing for him as a man, but only what he can provide for her and her vision of what her family life should be
lie - his in-laws are necessary accessories to this "good family man" mental image, even though he knows full well what idiots they are and swallows their inanities every time they're around (they also mirror himself and Skyler in that Marie is entitled shrew v.2 and Hank is "good family man" v.2...this speaks to a larger theme about social expectations and the lies built to sustain them)
lie - this legit brilliant man becomes...a high school teacher. Why? To further fulfill the "good family man" image. Not just to himself, but to have other people see him as such and validate his ongoing lies.
Then comes the great equalizer: imminent death. And the entire house built on sand suffers a seismic shift, and it all inevitably comes apart.
Of course, he tries his damnedest to hold on to the image. Throughout his entire downward spiral, the old lies find themselves rationalized and supported by new ones.
lie - "for my family"...even though his seething, resentful, egotistic rage fuels everything he does going forward from the point of his diagnosis. He's played by the rules, strived to maintain all his lies, and life does this to him? What's the point of it all? A derplord son mewling daily about breakfast, who distances himself from his father's name with his "Flynn" phase? A wife who hasn't bothered to know him, and her fresh-minted pity party(from his twisted viewpoint) because her family image is about to unravel?
What's the damned point?
...and on and on and on. Jesse, Tuco, creating the Heisenberg persona, Mike, Gus all the way to Hank....his unfettered id won't let him seem less than his brilliant self anymore, he has to make moves to show how hes smarter than everybody he comes across, he has to win. All steps along the way rationalize/justify former moves. It all falls apart anyway.
Point being, Walt is literally an exemplar of The Joker's "one bad day away from chaos" theory. He was always a monster. The mask of civility just gets taken away, and the entire show is about him scrambling to maintain and failing...and moreso what fallout that kind of revolving system of lies brings.
