But can people explain to me why a Skrull magician choose to cast a world ending spell, a spell that he volunteers when asked ( he could always say no ), where he gets pushback from his colleagues Wong, and he still does it.

Why would a Skrull who is trying to remain secret do such a thing? A Skrull must have a goal even if the goal is just to remain secret, what goal is this furthering? And why didn’t he do world changing spell prior to Peter asking him? What makes this specific request special?