Why am I addicted while my friends are not?
People’s brains are different. Some people are less sensitive to dopamine, others have trouble turning their dopamine response off.
Both genetics and environment can influence how people respond to intoxicating behaviors and substances. For example, those who grew up securely attached to their caregivers are less easily stressed. Those who did not are more edgy, and other research has shown they are more vulnerable to getting hooked. Similarly, your porn-using friends with partners are somewhat protected against addiction due to the benefits of touch and companionship. You may be more vulnerable while you're on your own. Masturbation doesn't relieve stress as well as intercourse.
Today’s superstimulating versions of food and sex appear to put a lot of us at risk. For instance, seventy-nine percent of Americans (and even more in a handful of other countries) are overweight. It’s unlikely that childhood stress made them all vulnerable. Too much fattening food itself has a drug-like effect on the brain. It decreases sensitivity to pleasure and promotes bingeing. Your porn use may have had a similar, drug-like effect on your brain, causing you to binge to the point of having adverse effects. See Your Brain On Porn video. As of 2016, close to 30% of men who use porn are reporting problems, or testing as having problems. (The first of those two studies also reported that half of porn users have escalated to material they once found "uninteresting" or "disgusting." Streaming porn thus appears to be changing the brains of 1 of every 2 users in unhealthy ways. For more, see Studies linking porn use or porn/sex addiction to sexual dysfunctions, lower brain activation to sexual stimuli, and lower sexual satisfaction.)
The other thing to keep in mind is that free, streaming Internet porn has only been available to most users for a decade, and porn videos have grown progressively more extreme (stimulating). Extent and degree of stimulation matter, and effects seem to be cumulative in many users. Computer wizards who got increased bandwidth first were among the first to show adverse effects. Now the guys who started with highspeed are showing up with problems. Also, people who use more extreme material tend to escalate further, progressively numbing their brains. What will virtual reality porn do?
Not all users experience (or recognize?) what they perceive to be adverse effects after the same number of years of porn use. Some develop symptoms (or begin to find them intolerable) thereafter. You may simply be a trendsetter.