Upvoted for a sensible analysis of the problem. Want girls? Go get them. My experience is that a common mistake amongst academically inclined people is to expect reality to reward them for doing the right thing - for example men on LW may (implicitly, without realizing that they are doing it) expect attractive, eligible women to be abundant in the risk-mitigation movement, because mitigating existential risks is the right* thing to do, and the universe is a just place which rewards good behavior.

The reality of the situation is that a male who spends time attempting to reduce existential risks will find himself in a community which is full of other males, which, relative to other hobbies he could have, will reduce his pool of available women.

Women who spend time attempting to reduce existential risks will find themselves surrounded by guys, who are preselected for intelligence and high ethical standards.