I mentioned before that I was in the Football Manager Live beta, that it has no NDA, and that the economy wasn't working yet. Please keep in mind that I'm talking about a beta, and of course the problem might be fixed before the game is released. But I found it a good example of why game companies might want to hire an economist, like the makers of EVE have done.
In Football Manager Live, you start out with a small amount of money, and a daily income of about £100,000. You select a team of players and substitutes, all of which want a daily wage. Those daily wages are your only expense (up to now), so you take players whose combines wages are less than £100,000, and there you go. If you make a profit at the end of the day (or rather accumulated over several days), you can invest that money into buying better players from other managers. By having better players, and by winning competitions, your reputation goes up, and so does your daily income. So, does this sound like a good economic model to you?
If you said yes, or are a developer for FML, you overlooked a small problem: Nearly everybody will be clever enough to pay less wages than his daily income. So every day the amount of money in the system is increasing. Managers on average get richer all the time. And as they can only spend that money on player transfers, this causes a huge inflation in the market value of all good players. On the game world I'm on, top players can go for over £10 million, and the prices are constantly going up.
Now originally the idea was that if you buy an expensive player, you would need to balance the added income he brings by increasing your reputation and chance to win competitions against his wage and the money you pay for the transfer. But if you know that the same player will be worth more tomorrow than he is worth today, you don't need to worry about whether he wins games for you any more. You don't even need to worry whether you can actually use him in your team, or you already have far too many strikers (they tend to go for the most money). If you bought the player for £3 million, and sell him at the end of the season for £5 million, the trading gain you make far exceeds any potential effect of the player on your match win ratio.
So some people now play Football Manager Live without actually caring a damn about line-ups or tactics. They just scout the markets daily for promising young players, or cheap offers of middle-aged players. If the managers have been playing a while, they got the "judge potential" skill, which shows them how good a young player will probably become when he gets a bit older, huge advantage if you're trading. So they buy cheap, sell at huge profits, and quickly amass great fortunes. And the sad thing is that because they have their teams stacked full of superstars, they also tend to win games a lot. New managers coming later into the game don't have a chance.
Fortunately the devs are on the right track, and are talking about adding other money sinks to the game. I hope that in the release version there is something resembling a balanced economy. Hyper-inflation destroys economies, whether they are virtual or real.