Feminism, in its simplest form is about equality. So any normal feminist would be against sexism whether it's directed towards men OR women. Of coiurse you get asshole feminists who are very anti-men and see everything as sexist. But those are extremists.
Also, while I see your point about there being much worse stuff going on elsewhere (and I feel very strongly about that - particularly sexual minorities and children's rights, ie child marriage and FGM), I don't think that is ever reason to not both fighting the smaller problems in your own country
For example I often see people saying to gay people "don't complain - they'd kill you in Jamaica" or whatever. That doesn't mean you shouldn't fight for gay people to be able to get married, just becuase there's much worse issues for gay people elsewhere in the world
And the same goes for sexism. Sure, women in the UK and the US generally don't experience shit anyway NEAR as bad as women in other countries, but it would be lazy and inexcusable to settle for "almost equal but not quite" just because it's even less unequal elsewhere.
Legally, of course, women are generally equal in the West now. But there's still some social attitudes that, yes, need changing. You can complain that that means I'm trying to force my views on others. But I don't care really. I think racist and homophobic attitudes need changing as well. That's just how it is. You (not you personally) have the right to hold sexist or racist views. But I will fight for society to move away from those views.
