After a certain point in the game when you have build everything and then rebuild everything to be the most efficient layout. Caps are not really worth anything (other than reviving dwellers and Mr Handy's) i have a full vault and have build everything and upgraded everything and im in the process of swapping dwellers out for new dwellers to train their endurance first thing so when they level up they will have more heath. So caps have no use at this point in the game. Why not allow people to buy them for 50,000-100,000 caps seems fair give caps a use late game. Another issue late game is radio rooms serve no purpose at max limit of 200 dwellers (other than raising happiness) Why not have them summon wasteland trader's you can buy things from with caps. The more luck the dwellers has in the radio room, more chance of a higher tier vendor who sells better loot.