Every time I've engaged in debate over this, it always comes down to believing that the world is zero sum and there is a limited amount of "happiness" that can be distributed.

That may be true for some things, but for many decisions it is not true.

There is enough food to feed everyone if we choose to distribute it properly. There is enough housing to house everyone. etc. etc.

There may not be enough cardiologists or Dali originals ...