[cynwoody]

Which again, could mean we now have many tens of millions of Americans who have spent their lives learning specific trades that are obsolete and therefore have become wholly unemployable.

You mean, like, farmers?

Source

In 1870, 48% of the US workforce was employed in agriculture. In 2002, 2% were. Looks like a lot of new trades got learned. And the country got a whole lot richer in the process.

[freedom462]

Again, I note that this was back when we were economically capable of making the transition and making sure that Americans who had spend their lives learning one trade could still support themselves while they transitioned to a new trade.