1. Because you believe in gender equality
If you believe in gender equality, you’re a feminist.
Why not call it equalism, then? Easy: because female is the gender that’s been and still is systematically oppressed.
Sure, women can already vote in most countries, but this is a very recent accomplishment and a legal change is not a change in society or culture.
Think about it –can a society that until recently didn’t allow women to vote or open a bank account without a man’s permission be truly free of sexism with just a change in legislation?