They exist everywhere. I even got singled out by mod here who gave me a warning just for using the topic above in a post.
That being said, I own both platforms on various devices. On the Apple side of things, I have a rarely used full carrier unlocked iPhone 4S and a iPad 2. I also own two Android phones one of which is a Galaxy S2 and a entry level model I keep as a backup.
People have accused me of being a "fandroid" multiple times. The reason I use an Android phone is not only the audio chip in my iPhone broken, the larger screen is really nice.
I like to compare both as Macs and Windows computers. The iPhone is a closed system. End of story. Jail breaking violates the Apple EULA. I have a full carrier unlocked model. Thankfully I don't have to mess around with that.
With the Android platform, you can compare many of the different forms of hardware to a Windows PC. All the different devices built to run a common platform.
I like both and both have pros and cons, still, I think it's just insane to judge others by what kind of phone they carry.