Every now and then, someone pops up and asks this question, as if we have nothing to be bitter about. I personally, am well past the bitter stage of TRP, but every day more and more "bitter" men will be joining our ranks, and I just had an epiphany as to why these men "seem" so incredibly bitter:

This is the only place they can go to vent their built up frustrations.

Women have lots of outlets to say pretty much anything they feel like. There are no repercussions for them when they say something outlandish, so they never feel forced by society into holding themselves back. Men on the otherhand, typically have no one that will listen to what they are going through. So when they finally find a place where they can vent their anger and have people listen and understand, rather than demonize them, they go way over board and dump this massive load of bitterness that has been saved up for years.

Edit: this actually came to me as I was upvoting a really bitter post and I thought to myself... 99% of the people on reddit would downvote this guy...