AWS is not a virtual machine company. Virtual machines are just one of its offering. At AWS you must architect your software to use other AWS services as much as possible, and spin up minimum count of virtual machines, only when you really need it. Only in that way you pay really what you use and in most cases you will see that the final cost is cheaper than any other infrastructure.

This applies to the most of companies at small and medium scale. If you are at huge scale it might not apply to you.