Once upon a time, people generated most of their value with their muscles. When machines replaced muscles, people could still generate value with their brains because machines could not replace brains. So the original Luddite scenario never materialized.
Now that machines are starting to replace brains, a growing portion of the population has a rapidly dwindling ability to generate significant economic value relative to the machines. As time passes, machines can effectively replace both the muscles and brains of more of the population.
This is also why forcing people to work fewer hours will not help. The problem is not the number of jobs available; it is the number of people who can generate more positive value in that position relative to a machine. Eventually we will all be in the position of no longer being able to be a productive member of a modern economy; everyone believes their contribution to be indispensable until the technology catches up and it isn't.