If you, like most people, use a national currency then you are being swindled. There are two reasons:
1) Ability of a central power to print more of the currency you use.
2) The way the banking industry works.
The first reason harms you by eating away from the purchasing power of your currency. Say there are three people that want to buy a house. The first is willing to pay $145K, the second $150K, and the third $155K. If the first person is given $20K that is fresh off the press then he can raise his bid over $155K to buy the house. The person who was given the newly printed money is able to price the other two people out of the market. The new money raises price of the house at the determent of the other two bidders.
The second reason is that the banks have an undeserved power. Banks make money off of the money they have on deposit. A bank doesn't loan its own money. It loans the money of its depositors. The need for this banking system is supported by the current monetary system. Another monetary system may rely less on banks and therefore interest would be lower.