It is useful to teach go for money while still an amateur. This is because strong amateurs are able to teach weaker players the basics. Income earned from this activity would afford more opportunities for the instructor to improve. People who can not afford professional services will benefit, and the instructor will moat likely improve at an accelerated pace, especially id the income generated is substantial. If you love the game, then go for it.

Not only the basics:)

Quite a few people have already figured this out

I don't mind amateurs who charge for lessons; I do object to kyus who charge for lessons.

But it's a free market, after all.

Do you know of any kyus that charge for lessons?

There seem to be two German kyus (IIRC, one of them was around 10k last time I checked) teaching at schools to earn money. I assume they are paid by the schools rather than directly by the students.

A few years back, there was a kyu (~5-6k) on KGS charging for lessons.

I don't see that as necessarily a bad thing. When I was a DDK, some of my best teachers were also DDK but just a few ranks higher. Without them though, it might have taken me far longer to reach higher ranks.

That said, it would be interesting if someone paid a 9 Kyu to teach them!

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Slava Ukraini!

There's been a few kyus trying to teach. Two of them stand out in my mind:

The first is Astone (David Munhofen) who was 5-10k if I remember correctly. He offered really strange teaching service packages on ebay at one time, and there was a very interesting GD post (sadly inaccessible atm) relating to his behaviour at his local club.

The second is Elmarias (http://dudisgoschool.webs.com/) who claims to be 2d but is likely closer to 5k. It was a lot of fun to look through his comments in his "teaching games" on KGS back when he was active. His site (especially the "tsumego" section under lessons when it was public) and his reported rank "progression" from his senseis page history are both quite interesting too.