How comparable are the collapses of the USSR and the western Roman Empire? Is it insane to look at them as analogous with the population decline and economic consequences of the USSR's collapse being an accelerated version of the gradual process that followed the fall of Roman administration?

Humans always like to make these comparisons as we are heavily programmed to look for patterns and similarities. But to say it was exactly like the fall of Rome does a disservice to the nuances of either event. That said it's not insane, it's human nature to draw these comparisons in hopes they help us predict some future catastrophe.

If you're interested in the collapse of the Soviet Union, there's a book called The Patriotism of Despair that deals with this subject but focuses more on the immediate aftermath of dissolution rather than the events leading up to it.

I wish I could answer you more specifically but I just don't know enough about Rome to make any meaningful comparisons.

However if you are interested in the book I mentioned I'd be happy to share it with you via .pdf.