There is hard data that shows "Bernie Bros" are a myth

A few weeks ago I penned a story for Salon attempting to qualitatively disprove the Bernie Bro myth by pulling from psychological theory and the nature of online behavior. To summarize my conclusions: First, there is a general tendency for online behavior to be negative, known as the online disinhibition effect — but it affects all people equally, not merely Sanders' supporters. Second, pundits systematically ignore when other candidates' supporters are mean online, perhaps because of the aforementioned established stereotype; in this sense, the Bernie Bro is not dissimilar from other political canards like the "welfare queen." Third, Twitter is not a representative sample size of the population, and is so prone to harboring propaganda outfits and bots such that it is not a reliable way of gauging public opinion.

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"Bernie followers act pretty much the same on Twitter as any other follower," Winchell says of his results. "There is one key difference that Twitter users and media don't seem to be aware of.... Bernie has a lot more Twitter followers than Twitter followers of other Democrat's campaigns," he added, noting that this may be partly what helps perpetuate the myth.

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Bernie followers act pretty much the same on Twitter as any other follower. There is one key difference that Twitter users and media don't seem to be aware of. Bernie has a lot more Twitter followers than Twitter followers of other Democrat's campaigns.

People responding to hundreds of millions of people online tend to dehumanize others. They remember that someone is female/male or follows some candidate or is of some race, but they frequently don't pay attention to differentiate actions of one member of that group versus another. So rather than consider how frequently an individual of some group acts, they think of how frequently the group acts as a whole. If they interact with many more members of one group than another, that perception of the group is magnified by the number of members they see.

https://www.salon.com/2020/03/09/there-is-hard-data-that-shows-bernie-bros-are-a-myth/