Sex is the most sacred of acts, since it produces a new human life. As such, when it's "distorted/ corrupted" it becomes the most dangerous of acts.
Never gave much taught to this stealing energy angle, but I'm willing to go with it. However, I would say that we can even analyse it, from a much more "material" perspective, and is still something to consider.
I became aware of the physical damage of masturbation a couple years ago and of porno in general, about a year ago... And it is scary.
I believe it is one of the, if not THE root cause, of most issues facing the world and western society in particular. Guess, I have a lot to say about it, but this is a nice succinct way of putting it. (Maybe I'll write a post someday, but yeah, be it physical, mental or spiritual... porn is a severe treat)