Obviously, it wasn't becoming a meth kingpin and leaving a trail of bodies in the process. It was that most people know the occasional feeling that we have somehow been screwed over. That we aren't living the life we are supposed to have. Whether it was our former co-workers, or friends or just the whims of fate, we look around and wonder what the hell happened.
And what made Walter White so popular, even in the face of his increasingly murderous and evil actions, is that he pushed back. Whether it was attacking the bullies that mocked his son, blowing up Tuco's office with fulminate of mercury all the way to forcing Gretchen and Elliot to provide for his family (which provided the best quote of the night as seen in the title), he refused to be kept down by what he saw as unfairness.
Obviously, this was also mitigated by his hubris, a ridiculous ego that got him in trouble time and time again. Who can forget him, drunk on wine, being offended by Hank thinking that Gale was Heisenberg? And getting him back onto the case that was all but closed. But in the cold of a New Hampshire winter (being born there, I can tell you that it can be very cold indeed), hubris and ego were stripped away. And we were left with the Walter we saw in the pilot. Well, almost. This is a Walter burdened with the horrible knowledge that all his sins weren't committed for his family or a greater good. He can't lie to himself anymore. They were committed because he was a greedy, egotistical, murdering psycho. But it is also a Walter who again refuses to lay down, this time so he can make things right.
It's the one time in the series where his flair for lying is only used on others, as opposed to also trying to convince himself he serves a greater good. He feeds into the fear and, in my opinion, guilt that Gretchen and Elliot feel to ensure that his family will be provided for in the end. He uses Lydia's regimentation and murderous impulses against her to ensure that not only will she die but that he will get inside the compound. And it is telling that the only lie he tells to Skyler is that he is broke, so that she and their children will be okay in the future.
There are some people not happy with the ending, that don't like that Walt "got away with it". But that is untrue and misses the point. Walt got away with nothing. He lost his family, his home, his reputation, his money...everything. He is a decaying shell of a man.
But what he did find was the smallest bit of redemption. That in all the muck of the drugs and murder and evil he committed to "provide", he pushed through and up and was able to claw back just a piece of who he was before all this began. And that isn't a bad thing. We should all hope that anyone, no matter their crimes, can be redeemed. Can face their actions and own up to them. That they can push back against their own badness and try to reclaim who they once were.
Even if the story was fantasy in some aspects, in the end it was a very human story. All of our frailties, impulses good and bad, the depths to which we can sink and the strength we can find to try and fix it...we could relate to it and understand it. And it was that part that pushed Breaking Bad beyond the other shows and makes it the best television I have ever watched. And it will be damned hard to top it.
Plus, no other show will ever have this:
Yeah, bitch! Magnets!