What type of advice? User submitted content and advice (http://www.reddit.com/r/relationships), or a site where you write articles about 'the top 10 secrets to dating every guy should know'?

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.

Simple pickup are examples of guys who did it recently.

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...

I know people who make $1 million+ yearly in affiliate commissions in this niche. There are many info products, membership clubs and networks with 7 figure revenue and few with 8 figure revenue.

Example: http://www.pauljanka.com makes 7 figures. Source: http://mixergy.com/dan-caron-member-mouse-interview/

Judging by the advertisements on porn websites and lifestyle magazines online, as well as Cosmo and whatnot offline, yes.

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.

I think it's so big a niche that it doesn't qualify for the term niche.

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.

As others have said, yes, it's big. But it's also crowded. And it's hard to be clearly better than the existing players. (Or at least, hard to be clearly better in the eyes of those looking for advice.)

Reddit and StackOverflow exist.

What would you do differently?

How so?