It is a big niche, but it's also highly competitive, and you would be competing against people that are already well connected and established in the industry. I would say the chances of success are extremely slim.
The darker, and more dollars, can be found at /r/seduction and darker still is /r/TheRedPill/
Every few years there seem to be a fad about these things, HN used to have these pick up artist posts pop up regularly until about 2 years ago. I got the impression that there was a large SV contingent involved in the pickup artist scene which eventually spawned the brogrammer movement, though no-one openly discusses it.
Wild speculation ofc...
Example: http://www.pauljanka.com makes 7 figures. Source: http://mixergy.com/dan-caron-member-mouse-interview/
It's one of the most reliable sources of trouble for people, one that transcends language, culture, and time.
As long as you have somebody who is lonely or getting less action/attention then they think they should, you have a potential customer.
It's one of the biggest industries around. Large mainstream magazines are centered around it. TV shows are centered around it.
Not that there aren't ways for individuals to make a lot of money of differentiating themselves.
What would you do differently?
I can figure out my code and my gf in one stop?
http://area51.stackexchange.com/proposals/44577/relationship...