Im not giving numbers as I see it pointless, but its obvious that there are extremely huge cocks who will by no means be ever featured on a porn film.
Your point of view is as if "real life" had something to do with "porn life" which is obviously not the case. Do you remember this White Pony guy, one of the biggest porn actors of the past decade? Well, he never showed his face, his performed for 3-4 years only and then quit porn forever. He may now be a salesman, a lawyer, a builder or whatever, as 99,99% of well endowed men. He had an enormous cock but he understood it was not worthwhile pursuing a career in porn. Porn is not profitable for men, period, unless you have no alternative (which is the case of Nacho Vidal, a brainless bloke who tried hundreds of times to find a professional alternative to porn but nothing worked for him).
You seem to live in a universe where a guy with an enormous penis will always try to enter the porn industry, but thats false 99,9999% of the times. I onced asked a famous (and rather successful) Spanish porn producer if it was harder to find an enormous penis or a porn actor: he told me that he could find as many huge cocks as he wanted to, but the rare thing is finding someone who has the skills of a porn actor.
If you have never seen a really huge cock that's because you havent moved enough. Its as simple as that. I have attended a number of gyms along the years and there were always at least a couple of guys who would rank among the "porn size" level.
