The true issue is that as a tool, currency is VERY easy to use.
Anyone can use it.
Greed is a human nature thing.
Scamming people is a human nature thing.
Those bad things exist inside of people, not inside of the tool.
Currency makes all exchange easier. Thus, the bad sides of human nature can be expressed easier as well.
Like I said ALL tools can be used for good or bad purposes.
The true things you don't like occur inside the minds of people. Currency doesn't have a mind, or the ability to act except when a human uses it.