One reason I think he is a villain is the way he ruled people to obey him. For example after he conquered cities he sold 30,000 people into slavery and killed over 6,000 people to scare the people of Greece obey to him. He sold the slaves to the rich people so he can gain trust of the people.
Alexander the Great was very greedy wanting land, money and power. He wanted land to extend his empire. And with that, gaining more power among the people. He sold people as slaves for money. Although Alexander the Great seemed generous to some people but he's really selfish