Democrats tend to be more emotional. If you slight "their" guy, I think you end up with more of the same as 2016. I believe there were a lot of Sanders voters that felt so betrayed by the DNC nominee process that their vote, if they voted, converted to "anyone but Clinton."
Poll: 1 in 4 Sanders supporters won't vote for Clinton
Wikipedia page for 2016 DNC primaries
13,206,428 Votes for Sanders in the various Democratic primaries. If 25% of those people really didn't vote for Clinton, that's 3,301,607 votes that she missed out on. I don't have any way of determining just how those people polled, actually voted in the presidential race, that would have pushed Clinton's popular vote total up another 3M for a total of 6M above Trump.
Take a look at Michigan: 598,943 votes for Sanders. 25% of that is 149,735. Hillary lost Michigan by only 10,704 votes.
I imagine you could find a trend for many of the states she lost that she considered a lock.