If Pascal's wager can be applied to belief in anything, then what is the fallacy in Pascal's wager?

I want to know the specific flaw in Pascal's wager that allows it to motivate belief in other things than God. For example, a similar argument to the original wager can be used to say that it is prudent is to believe in the devil, or that black magic works, or, really, any unlikely belief that might have some potential benefit. If the wager justifies many cases, doesn't this weaken the argument, in the case of God? If so, what is the flaw in Pascal's wager, that makes it seem like a proof of something, but cannot be, since it leads to contradiction? Is there a named fallacy, to describe this example?