Why what? Why do I fight injustice and sexism? Or why do I think sexism branded as feminism is a such a colossal problem?
The former is pretty obvious, I think few people in the west think sexism is a good idea, personally I subscribe to a pretty mainstream individualist moral stance. I wrote some thoughts about this in some parallel comments:
https://news.ycombinator.com/item?id=13737987
https://news.ycombinator.com/item?id=13737437
As for the latter, that's a much longer discussion for which unfortunately I do not have the time to get into sufficient detail. Nor do I think this is an appropriate forum for this discussion considering all the downvotes I am getting (no complaining, just stating a fact). Oxitendwe (in this thread) has briefly touched the crux of the issue, however. Mainly that is an attempt of a power grab over society, one that fundamentally has very little to do with women, and in the end it will cause more harm to women than men. I, and most likely my children and friends are directly affected by this power grab.