Could you replace with "throwing resources into it", per previous Landsburg reference? [or even "throwing diamonds into it".]

I was going to say something similar. However, note that the digging of the hole in order to dispose of money actually is wasteful - personally I"d probably replace with "digging a big hole and immediately filling it in again", as that is not only uncontroversially pointless, it is also almost the canonical example of a pointless thing to do.