It is absolutely true that most of the things we do are unnecessary. You have cited doctors as one of the examples. Here, doctors perform some tests that are unnecessary and their purpose is only to make patients spend extra money and make money from them. Whereas if we could live in a clean environment and live socially without loneliness and could eliminate weight and depression, then we would have a new life where we would not get sick so easily.
We should be improving our ability to improve, rather than fighting diseases we have given ourselves.