The thing is, there is a set limit amount of dollars in circulation in the US. There is a finite amount of physical dollars which is calculated to make sure values of items stay stable. Thing is in VMK, credits are pumped into the game non stop through mini games. Mini games themselves cause inflation, but at much slower rates. That's why we haven't seen another "double credit day" because it pumps credits at really fast rates, inflating prices because everyone has tons and tons of credits, making items super expensive since it's easy to get credits on those types of occasions. That's why mini games in MMO's are usually difficult to play with very little credit reward, to make the inevitable a slower process. In concerns to Gift Cards, it makes credits itself a trading item. In original vmk, credits weren't a trading item. Only few people traded for credits because it was difficult due to how easy it was to scam, and wasn't popular. When you trade credits, everyone begins to have tons of them. For newer players who try to "get rich quick" just slave themselves to mini games to make tons of credits to trade them for items. The result now is that everyone has tons of credits. If everyone has credits, it makes them less and less valuable. Now that everyone has all these credits, they have high purchasing power, being able to buy things that become retired at much higher rates, (aka magics). Magics can be bought so much more easily now since everyone can just trade junk for a gift card and magics become devalued. I know this may be a little confusing but it's economic law really and it is super important to keep the rate of credits in a game as slow of a process as possible. And also, the US government actually shreds money, literally to make sure the amount in circulation stays stable. Hope this helps!