No real group, or even an imaginary group? I mean, take the "misanthropic losers" you described (and for the sake of debate, let's assume your description of them is completely accurate), and imagine exactly the same group with genders reversed. Would it be okay to call those women publicly "losers"?

Well, we can imagine anything we want to. It's not hard to think of a possible world where some loose subculture or organized group of women could be fairly characterized as "losers" on a par with redpillers. You could basically get there if, say, radical feminism was a lot more dysfunctional than it actually is. No such luck, though.

How about a group that achieves real results?

Perhaps you're missing the point here? By "achieving real results", I obviously don't mean committing assault. Even successfully influencing politics would be a dubious achievement, as long as their basic ideology remains what it is. However, it is indeed a stylized fact in politics and social science that such nasty subcultures and movements generally appeal to people who are quite low either in self-perceived status/achivement, or in their level on Maslow's scale of human needs.

Your quotes from the Manosphere blogger were quite sobering indeed, but I'll be fair here - you can find such crazies in any extreme movement, so perhaps that's not what's most relevant after all. If most redpillers stuck to what they might perhaps be said to do best, e.g. social critiques about the pervasive influence of feminized thinking, the male's unrecognized role as an economic provider and the like, as well as formulating reform proposals (however extreme they might be), I don't think they would be so controversial. Who knows, they might even become popular in some underground circles who are quite fascinated by out-of-the-box thinking.