I think the fundamental issue is that so long as NMR is completely disconnected from the actual performance of the fund it has no fundamental value aside from its ability to be used to earn more NMR.
NMR is being used to earn dollars, meaning that is should have a real fundamental value, but that usage is only by numerai (by paying NMR for stock predictions which they turn into dollars). For everyone else, NMR is just a means to earn more NMR, and because numerai has what is, practically speaking, an unlimited supply of free NMR, they don’t actually ever buy NMR with their dollar gains and create demand.
A buyback from the fund based on the fund results would be an affordable way to keep things as they are but introduce dollar based demand for NMR into the system and I think is the simplest solution to the problem. I wrote up a proposal here: Leaderboard Bonus Replacement -- Metamodel peformanced based NMR buyback
For comparison, a token like BNB has a direct connection back to dollars because at a fundamental level it is redeemable to pay binance fees (which otherwise would have to be paid in dollars/btc). Binance is the only entity collecting fees in dollars in the BNB ecospace but they tie the currency back to their core business model (denominated in dollars/btc) by ensuring that anyone who has to pay dollar dominated fees would want to buy BNB, thus providing price stability and effective sharing some of their dollar fee earnings with BNB holders who elect to sell their BNB.
Numerai needs to do the same and directly connect their core business model to the demand for NMR. Currently the connection between NMR and dollars is complete isolated to numerai and there is no tie-back to NMR holders.
Of course the other option is to do what they used to and pay a portion of tournament rewards in $, that would solve the problem too.