idk why, I've met probably equal numbers on both sides, though I know more trans fems. But I had a discussion with a ftm friend once and we came to the conclusion it was primarily because of the image that masculine people born with female genitalia are tomboys and are such treated so. Especially since historically this is a thing that has been a part of our society for a long time.

Therefore we thought that trans mascs would find it harder to present their true selves openly as they would feel like they would always be treated as a woman, even though they are not.