The market already has a mechanism for incentivizing putting capital to work, though. If something is held off the market ("hoarded", in your terminology), it r

The market already has a mechanism for incentivizing putting capital to work, though. If something is held off the market ("hoarded", in your terminology), it reduces supply, and the returns in that area go up, making it more attractive to do something with it. For money-wealth, the outlook is even better. If Scrooge McDuck, puts all his money into his basement so he can swim in them, he has removed those from the supply and increases the value of everyone else's money while he holds it off the market.