Username "degenerate" defines startup culture as equivalent to macho culture and wonders if women are as good and determined at work as men. Got it.

The words "bite the bullet / grin and bear it / do what needs to be done for the company to be successful, or it will fail" could also describe the job of a parent. Yet we don't usually think of parents as being warriors. Thanks for giving us all an example of assumptions about gender that cause huge problems, can I use your words as training material?

This point of view is absolutely absurd. Women and men are both obviously capable of hard work in the same capacity.

Yup, but not as many women as men. Thus you won't have a nice 50/50 mix that HR expects.