I don't think anyone is advocating a better world without believers. It is a better world without belief. Even you must agree that most beliefs historically and culturally are rubbish (Thor) ergo people are unable to differentiate between belief in something true and belief in something false ( without recourse to the scientific method.)
Where would society be now if people had never worshipped Thor and had instead spent that energy and time in scientific research? I suspect you'll see where this is going. Billions of minds pouring their energy into discoveries that will benefit future generations v people selfishly searching for personal supernatural fulfilment?