Because it’s very unlikely that we know everything there is to know about making computers work faster. It’s the same reason people like Malthus are typically

Because it’s very unlikely that we know everything there is to know about making computers work faster. It’s the same reason people like Malthus are typically wrong. He thought the world would be out of food by this point. But he never predicted (nor could he predict) the advent of fertilizer and modern growing techniques which vastly boosted efficiency in food production. People like this think the future will be like the past. But the future is never like the past because people solve problems. As long as people are solving problems they are creating new knowledge and making progress.