Watch the show. He is given multiple opportunities to walk away while getting everything he wants but continues making meth because he is an arrogant man.

All the despicable actions he did during the show (watching his partners GF OD and not intervening, running over two people with a car, poisoning a child, letting a child get murdered, collaborating with neo nazis, and selling Jesse into slavery) were not done to help his family but for his own selfish gains.

That’s like the entire point of the show, selfish man wants his own nut at the cost of his loved ones.

I've seen it three times beginning to end, most recently during the pandemic.

I get his evolution as a character as that's the primary theme, but it never would even be a thing is he didn't have cancer.

You remove this factor, no Heisenberg. Full stop.

The Gray Matter storyline happened at least 20 years before the events of the show began. There's no indication he would have broken bad/lashed out due to this, by all indications he led a normal life since then and is seen by everyone he knows as a upstanding, somewhat meek but respectable person with no outward character flaws.

The cancer diagnosis and its implications for him and his family is what sparked this. And he continued further down that path due to believing he was going to actually die. If you recall when he decided to get treatment and found out he was in remission, there was a moment of "wtf have I done" for his character.

The Gray Matter backstory, and his former cofounders re-entrance in his life due to perceived medical bills explained the peeling the onion that led to his shift.

He started out on that path because of the medical issues, but it's absolutely true that he continued it because of selfish reasons (that grow larger until the very end of the show).

Admittedly, the focus on debt was very small. The Korean shows put a lot more emphasis on it.