They could also accept pebbles and sand as payment, hold them forever, and pay the merchant with their massive cash reserve or 0% interest debt. Profit.
Unproductive investments are basically the constant increase in stock and housing prices over the last decade. You're not buying those to make more money, there simply is no other place for the money to go. The only way the savings rate can be reduced domestically is through unemployment or underemployment. Unemployed people don't earn money but they still have to spend, which reduces savings.
It's a truly hopeless situation for the humans living the USA. But hey, at least the dollar is still "good".
Oh right, presidents are taking on debt to cancel the savings glut that was forced upon them. That's a bad thing.