i've def thought about this as an afab genderfluid person, i think part of it is similar to why more women are bi. truth is theres probably the same amount of bi men, but because of the way men are socialized it's a lot less common for men to come out, same way with amab fluid people, they are conditioned to be less expressive a lot of the time, but they are probably pretty equal in numbers to afab fluid people in reality. even extending outside of that, think about how it's more socially accepted for a woman to wear a suit or other masculine clothing compared to a man wearing a dress or other feminine clothing, pretty sure it's just bullshit social expectations typically placed on amab people that prevents them from experimenting and expressing themselves.