The thing people are worried about is not a particular industry dying or a market change like the Great Depression (though there are people that argue that the

The thing people are worried about is not a particular industry dying or a market change like the Great Depression (though there are people that argue that the Great Depression, especially in a global context, was a major contributor to WWII) that corrects back into a similar economy. They are worried about a systematic removal of jobs at a massive rate, across the spectrum. So for instance, if you look at agriculture workers in the US it took from 1910 to ~ 2000 to get from 30% of the economy employed in farm work to ~2% (which is likely the minimum). Along the way you saw the massive labor unrest, cities had to be completely re-engineered, civil rights and family restructuring, 2 World Wars, etc. It is a reasonable fear that something like driver-less cars, which could impact a similar number of employees, could have just as big an impact, in a shorter time frame and that might not be all for the good. Its also possible that it was other factors that led to all that turmoil, or that we are better at societal change now, or that there is some new technology around the bend that gets unleashed due to this that prevents similar problems this time around. All of those are reasonable reasons to be optimistic (Pollyanna-ish if you will), but they don't cancel out the reasonable reasons to be pessimistic.