>The flipside is that there must be other work to be done or people starve to death
false. people are not helpless and jobs are not fixed in number nor social welfare gifts. Human creativity and industriousness can be put to task to produce things that other people want. In an absurd example, you could live next door to a new efficient sweater mill, and you could still knit handmade sweaters, customized with people's initials, etc., and their sale would measure the value of your output in. dollars. People don't do this very often because such an economy produces more lucrative jobs than that.
doomers have foreseen the end of the world in every generation going back. The bad speculations have never come true, but there have been some very negative outcomes of fearful people believing the doom and gloom, look no further than the seeds of Marxist revolutions, Fascism, and Naziism, they all start with people feeling economic uncertainty.
That is indeed an absurd example, as any number of failed Etsy stores - and failed businesses in general - confirms.
Trad econ makes no distinction between creative profit, which produces new jobs and new opportunities, and extractive profit, which destroys jobs and opportunities while trashing the planet's carrying capacity.
Both can make stonks go up, but one has a predictably limited life before it ends in catastrophe.
Unfortunately that life is defined in centuries, not years. In the meantime everyone gets used to normalcy bias, the extractive types own the main social communication systems, and when their backs are against the wall they will simply lie about what's really happening.
The collapse is always a huge surprise to most of the population when it finally happens.
And in the lead up to that it gets harder and harder to start a viable small business, because the resources needed to make it work keep going up, and the resources that are actually available to most people keep going down.
I'm not sure I understand your point. Someone who attempted to support themselves by hand knitting sweaters almost certainly WOULD be impoverished. So doesn't that support what you are calling "doomers"?