I am looking for examples where an old person could talk of the 'good old times' and these were objectively better than the current times. Large scale meaning it affected not just individuals or a group but, at least a large socially significant population of an entire region and long term means a scale of at least 50 years or so.
I believe this did happen between 1500 and 1650 in North and Central America. A significant proportion of the population died to infectious diseases from the Europeans, often well before the Europeans showed up in person. This lead to a general collapse of societies followed by significant reductions in living standards.
The fall of the Roman Empire, around 400 to 500 in Western Europe is probably another example.
Are there examples of this that happened after the industrial revolution?
It seems to me that since the industrial revolution the major catastrophes were either overcome relatively quickly (say WW II, by 1955 living standards in Europe were much higher than ever before) or were merely phases or slower growth (during the cold war, communist countries grew much slower than capitalist ones but living standards were still ever increasing).