Good comment! But this left me thinking:

> Thus a fight to death may be chosen, because the bigger team has good chances to win the fight. So chimpanzees start wars for the same reason why Russia attacks Ukraine or USA attacks Iran, those who have more weapons and more money believe that they can win the war, so they start it.

In the two Chimpanzee "wars" discussed in Wikipedia (Ngogo and Gombe) it was the smaller group that started the aggression. They were objectively at a disadvantage, but managed to kill or drive off most of the chimps from the larger group. It's as if being focused on aggressive behavior was their advantage.