I haven't followed the show, but there was a lengthy article about it yesterday, written by Jonah Goldberg. It was posted here on FR.
White isn't selling meth to pay for medical treatment. He's a high school teacher, and has decent health insurance.
He gets into the drug business because he doesn't want to leave his wife and son destitute after he dies from what was diagnosed as terminal lung cancer. There's even an episode (in the second season) named "Seven Thirty Seven". The name is from the amount -- $737,000 -- that White believes he needs to accumulate to pay off the mortgage, send his son to college, and provide for his family after he dies.
White vows to himself that he will get out of the meth business when he accumulates that sum. But, after he is told his cancer is in remission, he has transformed into a different person, who continues to build his empire because it has now become his "purpose".
Yeah, I made the same point in my last post.
And that is exactly where I quit watching. I realized he had become just another @*#&$^%*# drug dealer.