That Player don't do any treasure maps, he / she buys all materials on all Chaos & Light servers and pays for Calf Leather 400.000-475.000 Gil and for Frontier Cloth 60.000-78.000 Gil and he / she buys whole servers empty. So he / she can stock all his / her retainers with countless items.
It is not just 1 single server that he / she took over, it is 16 Servers. It goes on for years, many players know this, and that player got reported countless times and is still here. Don't tell me that 1 player hops between 16 servers to change prices on only God knows how many items every day, 2–5 times. Like I said, there are over 700 items on Twintania and many thousand items on the other servers. That player should have already reached the maximum Gil 40–100 times or even more. So what is he / she doing with all those billions of Gil? Don't you think that SE would control a single player with so many Gil? That Player wears since years the same Crafter Gear, he / she is only a Level 70 Bard + Crafting Jobs. Even if he / she uses this game as a selling simulator, which makes no point at all. If I did that and reached max Gil a few times, then there would be no more interest in doing so in this game. I would just move to another Game and try there my luck.