Why are a lot of men intimidated by butch lesbians/masculine women?

I’m a feminine presenting woman dating a masculine presenting woman. The hate and vitriol my lady receives from men has made me extremely bitter and angry towards men as a whole. For example, there’s a Facebook post where a butch lesbian from Boulder police is introduced, and the comments are flooded with ‘what is that thing’ among other hate comments… from men. We’ve had men chase us in stores saying they’d kill her. But at the same time, there are men who are respectful of her, like her friend who is a college professor.

I’m wondering if it’s an insecurity thing, because you’re not attracted to them, or… what? If you feel this way towards butch/masc presenting women, please let me know why. I’m just curious. If you don’t and can guess why other men do, please let me know why as well.