[PakG1]

That's difficult to say, because government investments mostly go into infrastructure and enablement policies, not ventures. But let's give it a shot.

USA: Green energy investments, of which some companies have turned out to be outright fraudulent.

China: Massive infrastructure and housing overspending and bubble, with much shoddy construction. Housing and construction companies everywhere benefiting from the money only contributing to a high-probability disaster ending.

Most Olympics-hosting nations, depending on what you perceive to be an acceptable measure of return.