I would find it extremely hard to believe any serious business would take RWTing gold in a video game as credible previous experience.
It’s all about how you present it!
I would call it something like virtual market analysis, research, and manipulation or a better title then just 'selling vidya game gold'. It'd be more theoretical work though, because with Sanct I don't believe it could be counted as actually working in a field - unless you're interning for R2P.
I think virtual market research and analysis sound great. Avoid words with negative connotations like manipulation though. Even words that are technically correct (like EXPLOITING a profit opportunity) can be interpreted negatively by human resources.
I'd recommend leaving it off the resume but bringing it up to an open minded employer. I don't think managers would really see it as a positive that you tried building a job on a game but if you have other employment it could be something you can bring up. I could see how you could leverage it though since you're basically running your own business, setting the bid and ask prices based on the supply and demand, and ensuring you have the required liquid inventory to maintain your business, the only problem is there's no one to verify this type of employment. I think you'd be better off bringing up a research assignment you did in school or through work than trying to prove checking people's threads for gold prices helped give you the relevant skills to complete the job.
The entire experience section of my resume consists of experiences in RuneScape, cryptocurrency, and the work I’ve put into my book so far. Everything is self-employment. This has not harmed me in any way whatsoever. So far, employers have been pretty fascinated and a few have even commented that it’s one of the most interesting resumes they’ve ever seen.
Again, it’s all on how you present it. There are skills you develop working in these games (depending on what you do). The hard part is describing them in a way that makes sense to an employer. What makes it especially difficult is that RuneScape has developed its own terminology for things that also occur in real life. For example, flipping and finding margins is essentially what is known as “market making” in real life. It’s essential to know how to describe your experiences in real life terms rather than in RuneScape terms. If you can do this, the employer will definitely realize your experience and transferable skills. (This is, of course, something I would be helping people with if I launch this service.)
I can imagine them googling it, finding random stuff about black market sales, breaking ToS, law suits against botting websites... and being totally turned off hiring you.. could always backfire
I have not had an issue with this so far.
But always be honest up front. Admit that some of what happens in the rwt industry (formally known as real money trade) is rather unethical and frowned upon. But be honest and tell them you weren’t involved in the unethical stuff (assuming you weren’t…

You can even go so far as to say this is why you would like regulation, taxation, or something else imposed to help protect individuals in the game.
Let them know that rwt is supported by some game companies and not by others. If they notice that it is “technically” against RuneScape’s ToS, remind them that this is NOT the same as being illegal! Also, throw out the statistics that the majority of players have rwt’d at some point (MMG’s quote). Be prepared to provide the source.
I like to compare it to monopoly money. If you are playing monopoly with friends and you are caught exchanging 20$ for boardwalk underneath the table, you’ll probably be kicked out of the game. But will you go to jail? Of course not!
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EDIT: I should also say that it is probably not too big of a deal that they can't "verify" you "worked" here in RuneScape. Realize that coming up with a fake story like this would be so absolutely difficult, that it is almost zero probability of it being an issue from the eyes of an employer. They will ask you questions about your experience, and you should be able to answer them clearly and concisely. Someone who is fabricating a story almost certainly will not be able to do this. So if you know what you have done (and obviously you do), backing up your story and showing the recruiter that this is a real story will not be an issue. And it is easy to prove that this industry exists. There is even some professional literature by academics on it. So you can always direct them to that literature in case they are skeptical that this industry exists.