I tried to do n-point arbitrage on a single service (e.g. US$-BTC-RUB-US$). The reason to stick to a single service was that moving money between services could

I tried to do n-point arbitrage on a single service (e.g. US$-BTC-RUB-US$). The reason to stick to a single service was that moving money between services could not be automated at the time, and, as the article states, a huge spread is required due to withdrawal and banking fees. While trying this, I got the impression that some people must already be doing this at large scale, possibly the operators of the service themselves. All types of n-point arbitrage I tried had zero return.