Well, I can't speak for all of the FtMs in the world, but to me, it seems like being FtM and being gay is actually pretty common. This is a bit of my experience; when I was younger, and didn't even know what FtM was, I had been raised (As most little 'girls,') to expect that I was going to grow up and marry and man and have kids. So...I dated guys. I thought I liked guys at that point, but I think that I just assumed I did, I wasn't really interested in them – but I come from a family of mostly women (I have two male cousins, a few uncles, and my dad...and that's it) So I got very jumpy around guys in general, I think because I wasn't used to interacting with them – I think that I mistook this for attraction in my younger years. But the older that I got, I began to resent my female body, and thus became very jealous of men – they had what I wanted, and that pissed me off. I went through an awkward lesbian phase, but I never felt attracted to the girls I was with – I didn't get those warm fuzzy feelings that you get when you're attracted to someone. After realizing that I was an FtM, I continued to date girls for a bit...but it didn't feel right, and I came out as being gay. So no, I wasn't always attracted to men.
'Wouldn't it be easier to be female and not be gay?'
No...because I am not a female. I could ask you, "Wouldn't it be easier for you to be a woman and be a lesbian?" But your answer will probably be, "No," Because it sounds like you're not a woman either. Gender identity and sexuality simply are not the same, one does not affect the other. They are independent of each other.
I've heard of plenty of straight FtMs out there. Believe me, they exist, but I am not one of them.