I don’t know how rational this is. Given how many soldiers have died so far, if I were a Ukrainian sent to fight on the front line, I wouldn’t expect to be coming back. Rather I’d hope that I contribute to the defeat of the enemy, so that my children or my comrades children don’t grow up under Russian rule. I’m not in their shoes of course. There’s no universal motivation so maybe what you say is more prevalent. That said, this war might not end without soldiers doing a lot more killing so “kill, kill, kill” might be an appropriate viewpoint.