Well, you shouldn't get into many fights in your lifetime. Honestly, I think if you've genuinely been in more than 5 real fights in your lifetime, you are either a bit of a troublemaker or you live in an extremely rough neighborhood. Part of self-defense is just staying out of trouble, and learning when it's actually worth fighting a battle or standing up for something.
Now, on actually learning how to fight or defend yourself if you aren't planning on competing, you never know when you may need it. It could happen sooner or later, but you never know. I just think it's better to be prepared and not need it than to not be prepared and need it.