Its not a zero sum. This will increase interest in other @Home projects. It's really wonderful that thousands of people can work together to solve interesting problems - all over the world.
For instance in LIGO gravitational wave detector one of PhD students accidentally misconfigured one of the black hole-neutron star merger simulation runs, so that it took months instead of days, but resulted in very detailed simulation, which then was used to study fine details of the observed signals.
It's hard to rationalize virtually any notions of conservation (being green, AGW concerned, etc) with this project. Finding the seed of pewdiepie's world is somewhere between absolutely meaningless and completely meaningless.