When the other markers wanted to fix the corrupted marker it saw this as a threat to itself and attacked everyone to save itself from dying.

I believe this because the markers are intelligent and since it is like a computer it should have a self repair and self preservation properties. I believe that the corrupted marker started to infect the good markers. It could be that they were successful to create good markers, but managed to make a mistake resulting in a corrupted marker that try to accomplishe the same thing only in a far worse state. I assume that the creators wanted to achieve a society that is immortal with limitless energy and knowledge resulting in the markers.

From this what we can assume is that the creators wanted to create something that can help their society live comfortably and wanted to spread this across the universe so that other societies could benefit from this and live comfortably too. Not only this, but the markers are intelligent, can store information, give information and can communicate with its sorrounding environment to evolve itself to become more compatible with its sorroundings. Not only this, but the markers evolve the necromorphs as time goes on to ubermorphs, regenerators and so on. The markers are supposed to have limitless energy and can revive the dead. We don't know who created the markers, but what we do know is what the creators tried to make the markers do.

Who created the markers dead space