If I knew how to make X several million dollars, I would probably also now how to make myself several million dollars. I agree that if I had make X several million dollars, it would be a good hook.
So you know my whole shtick is engineering marketing outcomes, right? I'm working for a client right now, doing SEO/conversion optimization/metrics/etc. It is quite reasonable to expect that I will increase their business by 5%. (I quoted a much, much higher number than that.) I could do that for myself, too, no problem.
Step #1 to making myself a million doing it: grow a business to where it gets $20 million in sales annual. Step #2: Successful A/B test.
Or, alternatively, make $CLIENT a million and get paid handsomely, without the "build a business for a decade" step.