What is it about excessive masturbation that makes it bad?

Only if....: Common sense. If you are in the grip of an obsession with erotica that's interfering with your making friends, fulfilling what you need to do as a spouse, enjoying other activities, or getting your work done, you may need a low dose of medicine and/or some insight/behavioral therapy. Otherwise, this isn't something you can do to excess -- unlike eating, drinking, or scratching, it's self-limiting.