The end of the world is always a nightmare. But when it comes with the System, then it's not a nightmare for everyone. Not everybody is ready to fall into despair and come to terms with their fate as zombie food. Some people are ready to keep fighting however they can.
Take Kasp as an example of one of those people. The end of the world was no nightmare for him. In fact, when the zombies and the System showed up, it brought new meaning to his life along with exciting new adventures! Our once introverted and antisocial hero now talks to people in real life even more than he ever did before the world ended.
And the System also granted him an interesting artifact. A zombie head that never shuts up for even one second. It was the best present for an introvert whose only talent was thinking.