If you can write it from a place of considerable contemplation and nuance, and turn it into a groundbreaking philosophical/psychological text that the next generation will reference, you could easily make a fortune because that would certainly set itself apart, and people certainly crave that. An example approaching this might be "men are from mars, women are from venus". But most people aren't capable of that, most people are terrible writers and thinkers. Sadly, there is a strong inverse correlation between intelligence and success with women. The most successful guys are typically average IQ and they are not gifted writers or thinkers. Most of these guys are surface-level thinkers who have egos that rely on their own experiences to make broad claims without taking into account the vast differences in individual circumstances let alone scientific/psychological knowledge from the likes of someone like Jung or Darwin. It's the same reason why most successful people are utterly worthless at giving advice on how they were successful - because they lack the critical thinking and humility to truly understand all the moving parts that led to their success. They say "if I can do it, anyone can" which is a completely absurd idea, many biases are at play here, but I'm getting off topic.
In the context of relationships it would be useful to go over deep level knowledge that isn't just based on actionable steps but a deeply thought out and well-written dissertation about female psychology, evolutionary biology, anthropology, cultural criticism, human nature, consciousness, etc. This stuff runs deep, but 99% of the content out there is surface level bro speak self-help nonsense. On some level, to do this righteously is to admit that some men will never find success. About 30% of men who have ever existed did not procreate - that's sexual selection in a nutshell, you cannot ignore mother nature and millions of years of hominid evolution. Gaslighting 5'4 Indian cashiers that they can land a 10 if they just work hard enough is insidious and cruel. We just need someone to tell it like it is, the good the bad and the ugly.
So, I say all this to say, you're better off just finding a niche, being a snake, and selling a dream to a target audience, gotta pay the bills somehow, I see nothing wrong with it. I am not familiar with BPH writing but looks like field reports. Would it be useful to some people here? Surely. But why bother? If we're talking a few dozen pages, then sure, go for it. But there are 2 decades of message board and Youtube videos on this, it's saturated enough as it is.
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