Even if we didn't now know for a fact due to Donna Brazile laying out in writing, that Hillary had control of the DNC during the 2016 primaries, and used it to box Sanders out, she still ran such an unlikeable, uninspiring campaign, with outdated and out-of-touch messaging, that I don't think she has any right to be smugging about anything.
If she had not chosen to (whether successful or not) attempt to ostracize literally ever demographic aside from 50+ white women by being actively antagonistic towards most of them (Millennial voters? Just laugh if someone asks how you'll appeal to them!), she very well might have won. Not to cast aspersions, but I sure don't call that 'smart'.
The sad thing is that our current predicament was mostly perfectly understood back in 2016, even prior to the election. But no one in the DNC, Hillary included, seemed to have bothered to learn from their mistakes, and are all still making the same mistakes.
...the fear is that if younger voters really are committed to a host of ideological positions at odds with the mainstream of the Democratic Party, then that Party, without a Trump-sized cudgel, is doomed. It should not escape anybody's notice that politics by negative definition—the argument, at bottom, that "we're better than those guys"—has become the dominant electoral strategy of the Democratic Party, and that despite the escalation of the "those guys" negatives, the mere promise to be preferable has yielded diminishing returns. At some point, the Democratic Party will either need to embrace a platform significantly to the left of their current orthodoxy, or they will lose.
There are only so many times one can insist that young voters capitulate to a political party's sole demand—vote for us!—in exchange for nothing.