Mike hated Walt because he saw himself in him
"You! And your pride, and your ego. You just had to be the man. If you'd done your job, known your place, we'd all be fine right now" Says Mike during his last meeting with Walt. But even tho it's completely valid, this coming from Mike is a massive projection if you think about it through the lens of watching Breaking Bad and Better Call Saul.
The things that characterize Mike the most are his countless ego defenses. And unlike Walt that hides it under a very thin layer of excuses, who actually comes out about it in the end, Mike's countless layers of delusion are actually something he takes with him to the grave, leaving even a huge chunk of audience to feel bad for him and saying he was not a bad guy.
"There are good criminals and bad criminals" "I'm doing it for my family" "No half measures" "The moral code" "I'm just a soldier following orders" are the biggest ones I can instantly think of. They allow Mike to avoid reflecting on who he actually is, but it's all a charade.
Let's focus on the biggest one. "The provider" narrative. You always hear people say "Unlike Walt Mike actually did it for his family with no ego" but is it actually true? Well, if we use simple arithmetics, this argument kinda falls apart. Mike is immensely overqualified for practically any job, he has an insane amount of honed skills and, most importantly, he knows how to show them off and prove himself. Mike wasn't dying in 1-2 years, unlike Walt, who had legitimate reasons to be worried about the financial future of his family. Mike's family wasn't even doing that badly. A modest trust fund or a legitimate, quiet job could have easily secured a comfortable future for a child that Mike cared so much about. Instead, Mike chased bloody millions through high-stakes cartel business. He wasn't working to keep the lights on, he was feeding a deeply entrenched masculine provider identity. After failing to save Matt, Mike used financial provider role as a desperate attempt to retroactively balance his moral ledger with absurd amounts of money.
But it's not just that. As you can probably remember, Mike actually secured all the money his granddaughter could ever need way before he got deep into cartel business. For helping with Hector, Gus organized a legitimate-looking, high-paying corporate contract as a "security consultant" for Madrigal for Mike, so he could launder $250,000. The job was designed to be a purely paper transaction. Mike was supposed to stay home, do absolutely nothing, and collect massive, clean, and legal paychecks. But instead of accepting money, Mike decides to infiltrate Madrigal warehouse without consulting anyone first, just to prove he can. While Mike uses the practical justification that a paper-only job is "too sketchy" and wouldn't survive corporate audits or IRS, Gus obviously knows his stuff good enough that he wouldn't let it happen. The actual reason was that Mike couldn't just sit back and do nothing, while receiving paychecks, he had to be on the grind. Also, potentially, sitting back and receiving laundered money from a drug lord would allow Mike to self-reflect on not being a good guy, so by putting on a vest and yelling at the warehouse stuff he could trick himself into thinking he was an honest worker with a job. Also just look at the way Mike acts in those warehouse scenes. He takes massive satisfaction in being smarter, more observant, and more competent than everyone else in the room. He couldn't just "know his place" as a quiet associate of Gus’s empire; he had to be the big dick alpha professional in the room. This was the last chance for Mike to give Kaylee a good life while keeping himself out from going too deep into dirt. "If you'd done your job known your place, we'd all be fine right now"
The best psychological characterization of Mike and his immense ego, stripping back all of the stoic armor, you can see in the show, actually comes from an uncomfortable scene some might have not paid too much attention to. I'm talking about a group therapy scene in Better Call Saul.
Processing his level of trauma required vulnerability, humility and facing the reality. Mike lacked the courage for that. Instead of looking inward, he used his well-honed observation skills as a weaponized distraction. By spending weeks of therapy, focusing entirely on sniffing out a fraud, Mike tried to keep the spotlight off his own rotting conscience. He doesn't do this to protect the group; he does it because his ego demands he be the smartest, most perceptive adult in the room. He turns a grief support group into a goddamn interrogation room. He uses his detective work as a weapon to humiliate a pathetic, lonely man and, by extension, to demean everyone else in the group for being "wrapped up in your sad little stories." Mike's ego demans absolute logic, completely ignoring the fact that therapy is a space for emotional vulnerability, not a fucking courtroom.
Mike looked at those genuinely grieving people and felt disgust. To him, their tears and trust and empathy were signs of weakness and stupidity. His smug attitude screamed that he was too "advanced", too hardened and too perceptive to be grouped with these inferior normies. By proving he was a better detective than they were, he gave himself a perfect excuse to reject the entire concept of therapy. In his mind, if the group could be fooled by a fraud, then the group's collective healing was a joke, and he was completely justified in keeping his walls up and doing it the "correct and manly" way, by burying it deep down and channeling it to continue working for a drug lord and being "a provider"
I think the most damning moment of the scene is that Mike's monologue isn't actually triggered by a liar, but by Stacy, when she confesses that she spent some time without thinking about Matty. Mike's ego is dependent on his grief. If Stacey moves on, then, in his mind Matty’s death fades, and Mike's self-imposed punishment/purpose loses its meaning. When Stacey displays a healthy step toward healing, Mike’s ego interprets it as a betrayal, but because he cannot safely attack his daughter-in-law for it, his ego pivots instantly, focusing on dismantling Henry, rejecting therapy and his organized crime "job" because somehow he feels more orderly and in control when it comes to literal chaotic criminal underworld than his own mind. Mike left a meeting feeling disgusted by a man making up a fake narrative for attention and free donuts, yet he goes on for multiple years creating a fraudulent narrative of a noble grandpa providing for his family.
And that's why I think Mike hated Walt, not just him being sloppy and volatile. In comparison to his own fortress of obfuscation, Walter was a mirror with no filter. Mike constantly speaks in calm gravely monotone, he's super competent, he doesn't (at least that obviously) give manic grandiose speeches about being "the one who knocks", so it can be easy to mistake his professionalism for some sort of morality. He also, unlike Walt, never strives to the one in charge, because being a "right hand" instead allows him to be the calm, competent and the smartest man in the room, while giving himself another defense of being a good soldier following orders, therefore partially absolving himself of countless ruined families, murdered people and child workers utilized by his boss.
Sorry if it turned out too long, or if I ended up repeating myself in some places. This was just a random poorly organized 1 am thought that I realized was harder to chew than I thought halfway through. Other than that, what do you guys think?