Governments generally remove excess currency from their economies via taxes. Every so often, say once a week or once a month, character tria and PPts accounts could be reduced by some amount. Might even make it progressive: some one hoarding 100M tria might take a 10% hit, while some newby with under 10,000 tria might not see any tax. Come back to the game after an extended absence, you might have no more money than a non-taxed beginning player.

That would reduce, but not eliminate, any advantage old timers might have in purchasing buffs or enhanced effects with their accumulated wealth.