The only way to do so is if you find a buyer IRL, but you're probably looking at taking a big hit on your profit. People can buy an item called PLEX for real money, which they can use in-game for a month of subscription OR they can sell it for the in-game currency, so you're already competing with those that are willing to spend real money on in-game currency.

But it's a frequent issue in other MMOs, where these companies will set up bot farms (or even pay people to play) to earn tons of the in-game currency, then sell it online. Officially it's not allowed by most games, but it's only illegal if you get caught.