If the “gold” in those online games can be converted to real USD, you can be sure the IRS would be interested in any income or capital gains that may be derived from the transactions.
all bandits are interested in all sources of wealth.
for govts, they just have to find a way to justify taking some of it
the only access the US govt has to any wealth is rooted in the 16th Amendment... which is basically written as if by a drunken sailor looking to grab any and all they can find.
the fact that it completely jumped around the states and went directly to the individual is irrelevant to the drunken sailor. prior the the 16th, the fed received its money from the states... giving them a level of power to negotiate with the feds. going directly to the citizen negates that ability.