This question already has an answer here:

What's to stop the Weasleys from simply creating money? Can't they create gold, silver, or bronze? Why not make muggle money and exchange it at Gringotts? Old clothes? Or just use a doubling charm when purchasing an item for infinite "new" clothes?

marked as duplicate by Valorum Apr 29 '15 at 21:31

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.