Sweeping generalization, no? And, it seems to me self-contradictory at the same time.
"stolen" is a straw-man. What is known is that the DNC and the establishment media heavily weighted the scales for Clinton and actively undermined Sanders. It is also fact that, early on, the media counted their estimate of the leanings of superdelegates to frequently suggest that Clinton was the prohibitive favorite and presumed nominee. It's also a fact that the DNC did nothing to correct this. These things went on for many months.
Anyone who pretends for a moment that such influences and repeated propaganda do not have any effect on an electorate, moving some to support the expected winner and others to not bother - (i.e. a self fulfilling prophecy) is engaging in self deception and worse. And you wonder why so many feel the Democratic Party is doomed? The blatant dishonesty of its many spokespersons about even the facts of what happened is certainly doing nothing to restore trust.