I agree. I'm consider myself to be str8 because I fall in love with women only... I adore EVERYTHING about women. I have never had so much as a crush on a guy or been romantically attracted to a guy... ever.
BUT... there's something about an aroused male that is very arousing to other males. Why do guys like 'hardcore' porn? Because it's got cock in it... cocks doing what cocks do. A cock that we can relate to. We relate because we have one.
How could any guy - straight, bi or gay - NOT like cock???
I agree with what has already been said... enjoying porn and using it to masturbate regularly would not constitute 'addiction'.
You know something is an addiction when it controls you rather than you controling it. If porn (and masturbation) stops you having normal relationships... interferes with work or school... or you have not seen your family in two months because you are jerking off in your room all the time you might wanna cut back or get help.