Not the same person but here's my take.

Self-help books are good if they address a very specific problem you are personally struggling with.

Like as an introvert, Susan Cain's "Quiet" helped me a lot. Or I had organizing problems at my job, and Marie Kondo's "Joy at Work" helped me a lot.

But if it is a random generic book like - 10 Habits of Rich People, or How to hack your mind and max your success, etc., they are either scams, or, they are a retelling of already well-known advice and not useful.