If you mean vidoegames or nerd shit, women have always liked those things and they were never exclusively male. It's like how lolita (though it is far more gendered than gaming or nerd culture) isn't technically exclusively female and we have some male figures who have been into it forever so a lolita only event wouldn't technically exclude men, brolitas, people who wear ouji, or something like that.
If men wanted to make something, call it male-only, rather than "x-interest we perceive as male dominant but actually has had women interested in it forever" only. Also bc I know you'll bring it up, the girls joining the boy scouts thing was dumb, but the scouts should have updated their programming so that girls and boys both learn the skills of both groups considering any functioning adult benefits from homemaking skills and outdoorsy skills and the financial management stuff the girl scouts is kind of pushing with their cookie empire nowadays. Keep it gender separated sure, but teach them both life skills, not one group how to peddle cookies and the other group citizenship, respect for nature, and wilderness survival as if women never go camping.
If there was ever an event that was a men's only con for any subject, cool, I won't attend, I don't wanna be around a bunch of dudes. But don't demand men be allowed into a women's
con that's literally just hypothetical just because men feel entitled to everything (not you specifically, but the guys here trying to call women mentally ill for not wanting to always be around men at every waking moment).