Publishers won't publish a book that says "If you can't make it, then, well, you can't really make it, haha".
Someone has to do menial boring depressing work. In a way, I'm doing it right now, fixing some bug in a barely profitable web application. Thankfully I'm not washing floor or flipping burgers though. But somebody has to do it.
Who is going to win in life anyway? Nowadays luck and opportunity is everywhere, a pretty girl from a third world country can make thouthands of dollars streaming videogames on Twitch. If she's not stupid and lazy, success is guaranteed.
The book is going to speak to some people and that justifies it's existence. Even if some people fail to become truly good and end up pursuing something they are not passionate about, it's not that bad. Many people say life is not about destanation but the journey. In that case the book is somewhat bad, because if you're not passionate about a journey, then your journey probaby was unfullfilling.
Some people just lack passion, they can't get excited. They need something else.
In general companies are unintentionally evil, stupid, and treat employees very bad.
Author's idea is not bad, when you compare it to wanting to become an expert complainer about gender inequality and monetize that. Although it can work. It does work for some people. Damn, I get a feeling that author's idea is outdated and today it's better to follow your passion, instead of becoming good. Doing both are obviously superior. But you can win whatever your passion is. In most of the cases.
If you are fat, ugly and lazy, you're not going to win.
I mean seriously, look at 6ix9ine he is a simple guy but he is winning. He lets his nuts hang and he is winning. He is not an expert musician, he's not lucky, he's just so passionate about making catchy music that he has some kind of personality disorder, borderline delusional, and yet... He makes millions of dollars and loved by millions of people.
Being best is no guarantee of success, and successful people are not necessarily reliable in attributing the actual reasons for their success.