There are plenty of things wrong with the world financial system, but this really isn’t one of them. Money that’s removed from circulation by being saved isn’t all that different from an economic perspective from money that is removed from circulation by any other means. The end result is that while that money is out of circulation, the money that’s still circulating actually has more purchasing power. There’s a big difference between actual goods and services and mere green pieces of paper.
In fact, if anything you should thank wealthy people for “hoarding” money, because so long as they do it means that the dollar in your pocket actually buys more.