There are billions of people on this planet with all kinds of interests, from the silliest softcore to the most extreme acts imaginable. Yet Paul seems to think there is only ONE kind of "porn" and only one kind of porn fan.
You can make money with almost ANY niche - if you know what you are doing. Scaling up is another matter but then there's so much lateral space available you can always widen your operation. All it takes is vision and endless hard work. And some luck helps.
