Why do you love sucking cocks when you have one?

Why do straight guys enjoy kissing girls when they have lips of their own? The answer is the same. It doesn't matter what anyone has themselves - what matters is who they are attracted to. Gay guys are sexually attracted to other guys so they find the male body to be arousing. Including the penis! Also people usually enjoy giving pleasure to the people they are attracted to (whether they are in love or just hooking up) and this is the best way to give pleasure to another guy. (at least in my opinion)