What became clearer the 2nd time around was that Walter White was a horrible criminal who's downfall was that he was greedy and didn't know when to stop.
Well, yes, it's fiction. My point is that Walter White, as a written fictional character, is written as a horrible criminal.
Pay closer attention to Mike's criticism of Walter's antics; or the general contrast between Gus, who is a professional criminal, and Walter, especially when Gus "fires" Walter. Ultimately, things end up poorly for Mike and Gus because Walter doesn't know how to behave as a criminal. (Or as a tech startup founder, for that matter.)