Just to clarify, the Constitution does not forbid the governments of the States from holding land. In fact, the equal footing doctrine dictates that the Federal government should have quit-claimed the lands of the territories when they became states. It didn't, in direct violation of the Constitution. Why? Congress was funding operations from land sales.
Congress effectively diluted the citizenship of those states when they did not quit-claim the land. As far as I am concerned, since the adoption 14th Amendmen,t this has been a violation of the equal protection clause.
They also obtain funding from mineral development leases. I don't believe such revenue is more than a token used to assert ownership.
If Congress wished to obtain serious revenue from mineral development, they would open all federal lands to entry and development, and IMHO, they would also license development of outer space resorces. Of course all that would encourage explosive development and growth of the economy, which is apparently not a good thing.