FantasyCraft has a neat system where one of the stats is "Prudence" and at the end of each adventure, the character will spend a fraction of the wealth they ear

FantasyCraft has a neat system where one of the stats is "Prudence" and at the end of each adventure, the character will spend a fraction of the wealth they earned, on a scale from 85%-25%. This doesn't necessarily solve the late-game wealth problem, but it does add a lot of flavor; treasures can be larger and the characters then spend most of it on living it up (or whatever).