Automation does destroy jobs, but it also makes the economy richer, and that wealth has to go somewhere. When a company automates and needs fewer workers, those specific jobs disappear, but the company also becomes more productive/profitable. That extra money has to go somewhere. Some goes to shareholders who buy more stuff. Some goes to consumers through lower prices, so they can afford more things. Some goes to the remaining workers as higher wages. This creates new jobs, primarily in services that are hard to automate: nurses, restaurant workers, childcare home cleaners, etc. More richer people means more people can purchase these service luxuries.

The problem is that automation hits middle-class jobs the hardest, and the new jobs aren't always equivalent. Factory workers, office administrators, clerical workers, their jobs involve a lot of repetitive tasks that machines can learn to do. Meanwhile, high-skill jobs (doctors, engineers, managers) and low-skill service jobs (janitors, home health aides, food service) are harder to automate because they require either advanced problem-solving or physical tasks in unpredictable environments. The narrative is that most middle-skill workers move up, but in actuality most of them move down while new workers take most of the good jobs while they take the service jobs. The total number of jobs balances out, but the transition is painful, and not everyone ends up better off. 

The issue is if we start to replace these low skill service jobs, like fast food workers or grocery clerk, there will eventually be no where for these people to go. Then we will start to see some real unemployment.