It is not a game or an investment, but a gamevestment (game and investment in the same time). If the game economy needs to restrict it to a single account, this is already a hint that is broken and not sustainable (opposite example where you can have as many account as possible, Splintemonster, dCity,...)
The fact that the beer stock is always full, is also an indication of the problem. People do not buy beer, because there's no real use case for it.