that's not just the smallest market it's the most troublesome market which is one of the reasons it's a hot potato. If you limited yourself to just nsfw you would still need the infrastructure to process any types of payments and still be at the bottom of the current players. You would be hamstringing yourself and it would be even tougher.

NSFW and borderline legal stuff (like phone spyware apps) have a chargeback rate that is way higher than traditional retail. Users buy porn then charge it back to their credit card when the post nut clarity sets in. When i worked in the industry that was the constant battle from the retailer side; processors like CCBill were the most lenient but even they would cut you off if your chargeback rate was too high and it was always right on the border. Even on sex toys the chargeback rate is more than double just selling t shirts and stuffies.

I don't know the financial side and have no idea why the chargebacks were such a massive deal to the processors. I can imagine being a small outfit it would be very difficult though if the margins were super thin.