Just how ignorant is this person? Because wow, you'd have to have pretty much zero knowledge of modern history to think this.
Like, just think about farming. A quick glance at Wikipedia indicates that 50% of workers in the US were farmers in 1870, and now it's less than 2%. One guess as to what caused the collapse in agricultural employment.
Cheap oil and the rise of mechanized agriculture that it has allowed. Petroleum products have made human lives immensely better over the last century or so. ...but there are also costs such as climate change and microplastic pollution. How great these costs may be and how they may impact us, that we are only beginning to understand.
By the time my grandparents were children, those days were over and they had to become farmers in Michigan. The family tried to stay in the performing arts but ever-increasing division of labor and modernization made that difficult.
I wish I had seen the days of vaudeville. The scrapbooks are amazing.
But this change may happen comparatively fast - perhaps over 10-30 years. So it might affect people in the middle of their career.