With the point "the velocity of money can be be significantly higher in a video game" you actually outlined a serious problem (and a potential solution):

The rest of the in-game economy (including its pricing) doesn't fit the money circulation velocity, thus we get problems.

The famous equation of exchange

> https://en.wikipedia.org/wiki/Equation_of_exchange

gives a rule of thumb how other factors of the in-game economy need to be adjusted if the velocity of money is increased.