This is the most underrated comment in this thread. Purpose is essential in ensuring one's mental well-being. Without it, you hit burnout or depression quickly.
I disagree, a sense of purpose is absolutely pursuable. It's merely a state of mind, a sense that what you're doing has meaning or makes progress towards a larger goal. What that meaning or goal is can be molded by conscious processes.
Everything in your comment can be true and the advice can still be useless. People need specific, small, actionable steps that they can realistically take. Generic stuff like "you need purpose" is either completely meaningless or inspirational in the short-term but with no real consequences.