I suspect that people say they are bi because somehow they think it means not gay. Yet bi just mean gay but not exclusively so or it can mean not exclusively straight. Six of one or half dozen of the other. The writer Gore Vidal used to say that there are no homosexual people only homosexual acts. Looking at it that way there is a lot more gay going on than there are people that identify as gay. Dr. Ray Blanchard, the guy that coined the term "autogynephilia" (AGP) also came up with the ten dollar term "gynandromorphophilia" (GAMP) to describe those who are attracted to MTFs. That would include both "chasers" and MTFs who are attracted to other MTFs. GAMPs, by his reckoning, are outside the bi/gay/straight paradigm. Like AGP, it's it's own sexual orientation. Personally, I could only be attracted to MTFs under two conditions: They were totally convincing as GGs with the addition of one part and they were tops. I've never met anyone like that in real life and the closest thing in fantasy would be what the Japanese call Futanari. GGs with detachable parts are just as good and they exist. Maybe that's just a variation on GAMP. I don't really know or care to tell the truth. The muggles just divide the world into people who are straight like them and everyone else is gay. That puts me in the gay camp by their reasoning. They don't care about our little distinctions and why should they?