Wait, did you just create an analogy between water and money and then claim that sticking water (money) behind a dam does nothing? Why do we build dams if they do nothing? Wait, don't dams usually have power plants with them? So you are saying that putting money behind a dam generates more potential for future money and allows one to store up a reserve for times when things are dry? Sounds like a pretty smart move to me to stick money behind a dam.
People who think consumption drives the economy don't understand the purpose of saving. It's not equivalent to burning money. And it doesn't just sit under a mattress in a bank account...