Sink HXD into the lands like increasing effectiveness of land using HXD to be able to harvest/hunt more efficiently on that land. lets say we have 5000 lands in game. spending 10k HXD each land to increase its effectiveness would mean (5000 lands x 10k HXD) = 50M HXD = 2.5M USD =~ 5 months of HXD emission.
Mechanics:
Lets say lands can have 10 levels of effectiveness, each level costs 1k hxd, which will improve the harvest/hunt speed, 1% each. So at level 10 a land will let you harvest/hunt 10% faster. which doesnt break the game but over time it has good ROI.
How it helps:
This means players who make 2k HXD everyday will need to reinvest 5 days of worth HXD to be able to max their land to be able to harvest/hunt better, instead of dumping it. Less HXD dump, more HXD slurped up from market. Value of the lands also go up as they are fully upgraded.