This has been examined in detail. Most of the Bernie-or-bust Sanders primary voters weren't even Democrats. They were Republicans and independents who supported Bernie in open primary states. Also, that percentage of crossover voting is normal. In 2008, 25% of Clinton primary voters and 9% percent of Obama primary voters went to McCain.
https://www.vox.com/policy-and-politics/2017/8/24/16194086/bernie-trump-voters-study
The only reason that it was that close in the swing states was because six million registered Democrats who voted for Obama in 2012 went to Trump.
https://www.bloomberg.com/opinion/a...crats-can-win-back-obama-trump-voters-in-2020
...and a disproportionate number of the Obama voters who stayed home were black, a demographic that barely supported Sanders in 2008.
https://www.washingtonpost.com/news...home-in-2016-more-than-a-third-of-them-black/
I'm sorry, but trying to blame Sanders for Hillary's loss is ridiculous. She ran a terrible campaign, and the Obama coalition turned on her as a result. This constant harping on a much smaller number of people who weren't traditional Democratic voters going third party or for Trump is a form of pathology.