shameful behaviors had come out of the cracks to support Hillary (!) in 2008 against Obama (apparently seeing him as the greater evil) and in the GE backed various choices against Obama/Democratic Party.
Then in 2016, a similar percentage, again hiding in the forest of regular Democrats but exhibiting the same-old identifying combo of "highest" principles and nastiest behaviors, joined Sanders against Hillary, and their victory is history.
BUT before that, in every election, strikingly similar noisy factions of similar minor percentages behaving in strikingly similar ways surfaced to support whichever LW candidate was likely to do most harm to the Democratic Party. Like Nader. When their candidate loses, most vote third-party or Republican to continue their righteous resistance against the evils of the Democratic Party.
They're only noticed when their sabotage threatens to be successful, otherwise mostly ignored and quickly forgotten. But they're the same sorts in every decade, old ones dying off, new ones coming of age. They'll change what they claim to support fervently with the candidate, but these ones are wired to dissidence, insurgency, opposition to "the establishment." -- i.e., the mainstream LW majority who always outvote fringe groups. That doesn't change.
Again, like their counterparts on the trumpian right, they are of course always motivated by only the highest principles, and their need to save the nation from corrupt Democrats justifies the nastiest and most ruthless actions they always must take. And the same for the leaders they find to support, who know that to have them they must feed their needs. Hillary in 2008 was a notable exception, but they used what they had against Obama spoiler.
Not our most self-aware sorts. They can and do spend an entire lifetime passionately opposed to the Democratic Party impervious to truth and without ever questioning their own motives or realizing that people and leaders who think and behave as they do should never be allowed to get power.