Are they? I mean you might want to at the absolute least cite some kind of study for this statement.
I know a lot of women in Tech, also quite a few at C Suite level, and the ones that seem the happiest to me are also married and have families, I'm not sure either gender does well past 45 having not had some taste of the most basic thing most human beings desire. Just my two cents. I also think about this a lot but as a man, to be fair to your point, why make myself so vulnerable to another person?
I'll leave you with an Arab proverb I love, "The (wo)man who never marries never knows, but the (wo)man who does, does.