The toxic Bernie "Bro" myth has always seemed to me like it's full of contempt for lower class people. I have to say, my experience of Bernie supporters online is that they are made up of a wide range of ethnicities and backgrounds and have a much better gender balance than other voters. The common denominator is that they rarely belong to the upper class, few of them are old white retirees, and they all cry out for real systematic change.
When I look at them I see people who are angry about the way their lives and futures are being sabotaged by the political establishment basically. Maybe that's tough shit to swallow for some people who have spent the last few decades waving party flags as the DNC descended into light fascism and oligarchy, but I don't think that makes it toxic behaviour. I just think it's a necessary reminder that a lot of people, especially the ones under 40 who grew up with the Internet and online culture as an integral part of their lives, are legitimately angry. The idea that they're more toxic than the people who have actually helped ruin their lives doesn't sit well with me at all.
I saw Bloomberg run a twitter ad about rude Bernie supporters recently for instance, and I thought: that's just beautiful. 40 sexual harrassment lawsuits from 64 women, countless of black lives ruined, literally spending billions and a media empire to buy an election, but what really matters to the establishment is that "Bernie voters" aren't civil when they tell him to go and eat shit.
Watching from the outside, it seems to me that American elections have been all about identity politics this century, but real, life-altering change comes from policy based in an unshakable belief of equality, not candidates that look like you.