Gaining and maintaining viewer sympathy for an anti-social protagonist The show "Breaking Bad" is about: 


  A struggling chemistry teacher turns to a life of crime with the aim
  of providing for his family's future.


The protagonist of this show is meant to be sympathized during the beginning of the show. During that later parts of the show, the main character commits atrocious acts. Yet viewers still sympathize with him. 

Why is this?
Is it because it is a TV show and not real life?
In a world where the Wealthy [are perceived to] abuse the Poor and Middle class, it is easy to subconsciously maintain sympathy for a 'honest' (passion to teach kids) and 'intelligent' (chem. teacher) person when they perform crime that it characterized in the 'Robin Hood' style.

I've never seen the show and so I'm sure that there are metaphors that make things more hazy than this, but these are broad societal themes in U.S. culture.