why men treat themselves as expendable?

when i used to talk about the conscription topic, i found some men who support drafting men only and not drafting women (not wanting to put women in danger). even in this sub. i understand not supporting the draft in the first place but supporting drafting men only?! not only that but many of them consider themselves progressive and support equality but completely fine when men become cannon fodder.

of course there are many women who are like that but there are also many men who are like that and that is what shocks me.

why do they think of themselves so little? why are they fine to be treated as cannon fodder? why do they have no problem with society sacrificing them for its goals?

is it social conditioning? is it genetic? is gender roles being imposed on them? is it their fear of being called cowards by others?

either way i pitty those men who don't mind being treated as worthless and have this internalized misandry.