In 2016 less Sanders supporters voted for Sanders than they said they would as well, thats the nature of depending on the youth vote for anything. They may vocally advocate for something online, but when it comes to vote in person those voices die down real fast.
That is true, he did try to go for voters that historically haven't voted and got the expected result.
Sanders couldn't bring in Warren's base once her campaign faltered while the moderates all united behind Biden, and then ever since Super Tuesday Bernie has gotten whipped 10% to 30% in every state.
But you'll notice that Bernie Bros are quite schizophrenic. They count Biden getting all of the moderate endorsements and Warren staying in until after Super Tuesday as "The establishment coalescing or whatnot". I have watched some Secular Talk and he keeps talking about all of these "smoke-filled backroom" deals and Obama making calls.
In reality, the Bernie campaign was trying to bank on all of the moderates staying in and splitting that vote until the convention, but that isn't how they see it. So, they are spiteful. That vote isn't completely negligible.
Hell Sanders even outraised and outfunded Biden almost every quarter of the primary, and Sanders has better name recognition now than he did in 2016 and he still somehow did WORSE than in 2016. In 2016 Bernie finished with about 1,850 delegates, this year he is sitting at HALF that, and California has already voted.
Yeah, he doesn't understand politics very well. If you look, he had like no endorsements, while Biden had tons. That just shows that he can't make deals and has no political capital to pass his legislation. All of that money can't buy you votes, fortunately. #NoRefunds
But let's not limit this to Sanders voters. Hillary in 2016 was also a more moderate candidate, but depending on the study, 9.2% of Obama voters voted for Trump or another that said 13% of Trump voters voted for Obama in 2012.
https://en.wikipedia.org/wiki/Obama-Trump_voters