Doesn't it seem that the rising "unemployable" cohort having all that free time, and the wealthy having none is not somehow related? "Unemployable" seems perjorative, so let's use Arnold Kling's ( Tyler Cowan's?) ZMP ( Zero Marginal Product ) workers.
You get the feeling that in years past, the ZMP would have been given some measure of slack, and allowed to work their way into a more productive status. But that's what's changed. I think there's been a cultural shift - look at the relatively unpleasant reports on how peoples jobs are now. Plus, unemployment ( especially if you're of an age to live with parents in their McMansion or even your old bedroom in a more modest home ) is a lot more comfortable than it used to be.
There's been a long-term trend towards advancing the age at which people join the workforce. People had moral reservations about the abolition of child labor - after all, it had worked out okay for them. It's only when unemployment began to be a more palpable problem that the mores concerning child labor shifted. Even then, my own father was pressed into service as farm labor as recently as the 1940s. This was standard.
As production has become less and less labor intensive, the workplace becomes more and more about social signalling. And as the population of firms becomes increasingly about maintaining old guard products and services and less about actually advancing the footprint of the firm from within ( with low cost financing enabling M&A activity instead ) firms are rapidly shedding workers. You don't even need offshoring or Chinese production to explain this. All you need is the Jack Welch "neutron bomb" effect.
We see increasingly ambitious tech efforts, not the sort of thing a half dozen people can do in a year or two, to sell for a few million.
But mainly, as the workplace becomes overtly inhospitable and the cost of slacking goes down, the equilibrium shifts.