Skyler: If I have to hear one more time that you did this for the family…
Walter White: I did it for me. I liked it. I was good at it. And… I was really… I was alive.
It is a gradual descent, but not so much that the viewer can be excused for not picking up on it. He kept going well after the point where he had made enough to take care of his family. He also could have accomplished his goal early by getting help from Gray Matter if he just swallowed his pride. And he was very willing to hurt or kill others as collateral damage, like Gale or Jesse’s girlfriend’s child.
Skyler: If I have to hear one more time that you did this for the family…
Walter White: I did it for me. I liked it. I was good at it. And… I was really… I was alive.
It is a gradual descent, but not so much that the viewer can be excused for not picking up on it. He kept going well after the point where he had made enough to take care of his family. He also could have accomplished his goal early by getting help from Gray Matter if he just swallowed his pride. And he was very willing to hurt or kill others as collateral damage, like Gale or Jesse’s girlfriend’s child.