What is it about BBC that makes us crave for it?

Curious cuck wannabe fantasize about sharing my woman with BBC only. The bigger and more aggressive the more it makes me wanna submit as well. I use to fantasize of sharing her and participating before. But after so long of fantasizing and watching cuckolding porn ive realized that i would never compare and accepted my role of just watching. Anybody else's fetish with black cock expand or progress to other kinks?