Most “bisexual” women just date men anyways. They just want to feel like a part of something and so they conflate making out with women for attention with being attracted to women. A lot of them think being gay or bisexual or whatever automatically makes you an interesting person. I’m sure if you asked them if they could see themselves marrying a woman and spending their life with a woman they wouldn’t be able to answer. Since they’re basically straight it doesn’t really mean anything other than them being an attention seeker. Despite that I do believe that bisexuals exist, I think it’s just a lot less common than it’s been made out to be.
Maybe 4Chan's real and more evil goal for attacking Tumblr was to drive Tumblrfags out of Tumblr so they could invade other websites, destroying internet culture an society, 4Chan are such retards if that was their idea.