Comment by OkayPhysicist

That's a pretty weak take. The difference between philosophy texts on ethics and the better self-help texts are just the difference between pulp fiction and classic novels. Time needs to pass before anybody is willing to go "actually, this is worth analyzing". That said, there's a lot of self-help that isn't philosophical (or, more exactly, don't attempt to defend the philosophy that they present the conclusions of).

Consider the difference between. "Thou shalt not kill, thou shalt not commit adultry" and "you shouldn't kill or sleep with your neighbor's wife because both actions cause more harm than they provide benefit, which ought be our goal because the conclusions of such a cost/benefit analysis closely align to most people's natural sense of right and wrong". The former is a statement of morals. If you include the "...because God said so, and God is always right", then it becomes an ethical argument, like the second. The key is arguing the why down to axioms, and defending those axioms as superior to other axioms.

A self-help book like "How to win friends and influence people" provides rules to follow, to achieve a desired outcome, and attempts to explain why the rules work. It doesn't spend much, if any (it's been a while) energy arguing why you should want the desired outcome, or if the desired outcome is actually a good thing.