Addictive & destructive both.
When I was 14 I was turned loose on a college campus for 10+ hours a day. I got a job in the A/V department, so I had access to a locked room with two fast (at the time) computers & internet access on a T1 I'd never been exposed (no pun intended) to porn before, & spent HOURS exploring the world of free porn.
Once the curiosity wore off, though, I quit. And I feel lucky that I did. I suspect that if I'd had the same situation & opportunity at 16 or 17, I wouldn't have been able to quit. As it is, I managed to escape relatively unscathed. I'm forever grateful for that, for my own sake & the sake of my future wife.
Viper GTS