Interestingly enough, it could be neither of those. The overconsumption of pornography, coupled with excessive masturbation, has the ability to almost completely eliminate the sex drive in the physical world.
Meanwhile, in the digital world, as one consumes more and more pornography they can become bored and start searching out more and more "exotic" fetishes.
I would suggest that he attempt to abstain from pornography and masturbation for at least a week, or up to a month would be the most beneficial, and throughout this time his priorities will shift away from relieving himself with pornography, and his sex drive and overall energy levels will increase.
Pornography is most certainly not benign and has major effects on the brain. Personally, I believe pornography is quite dangerous if used in excess and can affect people in the same way as the most addictive drugs.