I don't really get it either, but then again I'm terrified of spiders - doesn't matter how big or small, and even the non-poisonous ones scare me. So I understand phobias, and remind myself of this when somebody's afraid of my snakes.
I used to be scared of spiders
but I was at a reptile show and for some reason someone was selling tarantulas and thus conquered my fear of them and now I'm fascinated by spiders