You have the power to get your teeth fixed by someone. If you did not have money, you'd have to use other forms of power to get it done (calling a favor, threatening, bartering, etc), or perhaps you couldn't get it done at all because you lack any source of power that's sufficient.
None of those other forms of power are as efficient or effective as money (in fact, money evolved from bartering as it was more efficient) except for violence. However, we have (or at least are trying) to move away from violence as a society.
