I disagree, actually. Sanders shot himself in the foot as soon as he showed up and announced to America that he was a far-left socialist outsider running for president (essentially). As soon as the loyal democrats heard those words, he lost. Say what you want about Hillary's style of campaigning, but to the minorities, Hispanics, and African-Americans that helped her win the primaries, she chose to mirror herself in the eyes of Obama, which is what appealed to these demographics. While Sanders undeniably had a lot of momentum (surprisingly so for being a dude that showed up out of nowhere) and did a fantastic job of getting the biggest portion of his demographic (which is what, somewhere between 18-30 year olds?) involved in politics, the fact of the matter is that the very demographics that people claim would help him win against Trump didn't even show up in the primaries.
I mean, we could've had a President Sanders about now, but his message failed to deliver over Hillary's. Let's not pretend that Sanders is blameless in this situation, because he isn't. He lost very important states like Florida by a whopping 30 points and lost New York by 16 points. Those aren't measly numbers, people just weren't moved or compelled or as drawn to Sanders as they were to Clinton in these states. New Jersey even became a landslide win for Clinton, which is a state that Sanders desperately needed (along with California) to make up any sort of ground whatsoever, but he didn't.
Say what you will about the DNC conspiring to help Hillary win, but to the best of my knowledge, no DNC officials went door-to-door and forced people to vote Hillary. Her message naturally resonated towards those that were loyal to her and loyal to the party, while Bernie's fell on mostly deaf ears. He was a good speaker (a far better speaker than Hillary on all levels), but for some reason or another, failed to turn out his base (or attract any voters from Hillary's side) for the victory that he needed.
If we're going to blame Hillary for her faulty general election campaign, then it is only fair we should blame Bernie for his equally messy primary campaign. He's not flawless.