This is not a real person. This is the bank of a large RMT group that is involved in Synthing, Hunting, ENM, BCNM and KSNM. This is the banker where they take all the items; who in turn, obviously sells all of them. This guy will give other characters (i.e. Elvbbn) smaller amounts of Gil to trade to other characters in-game for real life money.
honestly what can SE do? we all know it is but there is no way to actually prove it if they arent under the same IP address and you can ban him for selling stuff