But the show never fully spelled out why Walt broke away from Gretchen and Elliott in the first place.
There were hints throughout the series. On several occasions, Walt accused them of cheating him out of his share; that bitterness seemingly helped steer him into his life of crime. But it wasn’t clear that his version was correct — in an episode where they confront each other at a restaurant, Gretchen said that Walt left her without any explanation. And the true story never came out.
“Breaking Bad” brilliantly tracked Walt’s transformation from teacher to criminal mastermind. But it’s still a mystery why that talented chemist turned his back on fame and fortune and became a humble high school chemistry teacher.
That is one secret Walter White took to the grave.
Here's my two cents worth on the descent of Walter White brilliant scientist to zombie science teacher. To a certain degree the first year of the show is the anti-Mr. Holland's Opus. There's more to being a teacher than getting a paycheck, Walt never understood that.
- Jessie tries to talk Walt into quitting reminding him that in the beginning all he wanted to make was 270k to see is family comfortable after he's gone. They now have millions so why keep going. Walt tells him that he sold his shares in Gray Matter for a couple of months rent before it got big and that GM is now worth 27.5 Billion dollars, he checks on it. Knowing what he could have had and threw it away has eaten at his soul all his life from that time on.
- When Walt meets with Gretchen and tries to get her to say they are paying for his treatment without explanation, this is where she says he left without explanation. Here it takes a little reading between the lines. Walt is verbally abusive to her. There was a reason he left and sold out. My reading is he suspected her of having an affair with Elliot, but wouldn't accuse her of it directly. The fact that Gretchen and Elliot then get married and go on to live on Mount Olympus reinforces his suspicion and animosity. It explains also why he won't take their guilt money or sympathy. Pride goeth before a fall, and it certainly applies with Walt in the first season.
- A quick scene where Walt and Skyler are looking at buying the house. She's pregnant with Walt Jr., he's working at Sandia Labs, which is much better pay than teaching. He wants a bigger house, she's conservative and wants to go small and get a bigger house later.
- The explanation for his lung cancer is that it came from his work at a lab, I think they said Los Alamos, but the other scene it was Sandia Labs. Could have been both or they forgot to have a continuity check between episodes. Reading into this, Skyler may have nagged Walter into leaving the labs due to the radiation he was working with, though it was too late. Skyler took a man capable of being a master of the universe and turned him into Harvey Milktoast. Walt was a brilliant mind forced to wander in the wilderness of mediocrity for most of his life.
- Face it Walter is whipped the whole series, nothing says this louder than after Jessie pours gasoline on their carpet and he's frantic to have it cleaned up before she gets home when they have a storage shed with over 80 millions dollars. Now that is one whipped man!
- I'm not dissing Skyler, she's right. All that money made them live in fear, it gets Hank killed, she's terrorized by masked men, they become destitute and Walt is on the run finally dying in a shoot out.
- Skyler loved Hank the school teacher and fights his every attempt to break out of the mold she forced him into. Hank hated his life and when he knew his days were numbered he equated love with money only his pride wouldn't let him accept Elliot and Gretchen's offer, and chose to make it outside the law. The tragedy of living outside the law is you lose the protection of the law.
- The ascent of Walter White from zombie science teacher to super meth cook was his death sentence. He finally admits it in the last episode that he did all of it for selfish reasons. Breaking the law and living in fear made him feel alive. Maybe taking a ride on a bull named Fu Mancu would have been better.