With wanker, I agree that masturbation is healthy. Healthiness is a feature of masturbation, but it's not its essential feature. The essence of masturbation is that it is a sexual relation with oneself. It's self-objectification. Calling someone a wanker is equal to saying they consider themself a worthy object of sex. If I read a book that doesn't do anything except try to make the author look good, I call that writing masturbatory. You should think about the difference between a thing's features and what that thing is.