philosophy

Initially, the Necromancers were driven out not by people, but by mages. And it was envy that was the reason! When the defeated Necromancers came to the people and began to preach "mass suicide," the priests naturally became alarmed. If the Necromancers had not been driven out of the empire, the Griffin Empire would have slowly but surely turned into one large cemetery, because, having gained enough power, the undead would have killed everyone who disagreed with joining them, and later turned them into "their own." And if the Necromancers themselves are so tired of life, why are they still in this world? They could have committed suicide, and that would have been the end of it. And there would have been no need to disturb peacefully sleeping corpses and FORCE them to fight for their own interests. Instead, they invent all sorts of ways to avoid death: Horcruxes, vampirism, spells... they are willing to do anything, just to stay in this busy and beautiful world for as long as possible. You might think they are AFRAID of death! And maybe they are. And in general, the philosophy of the Necromancers is wrong: you need to REJOICE in life, and in what nature and God have given you. You shouldn't try to cheat death; sooner or later, it will take its toll.

P.S. 2 Sergh: They were more at peace in the graves.

P.P.S. 2 AlexeyPank: NORMAL people study and research what they don't understand. Some of them later become mages (not necessarily the ones we know from Heroes 5) or simply scientists.

P.P.P.S. Not all people are like the ones you describe. Far from it.