There's multiple ways to look at the economy, the raw exchange of dollar currency in a debt chase (shit I need to run faster & pay down this stuff!), there's the productivity of industrial output (shit we need to sell more junk and useless crap!), and there's the stock and productivity in optimal life cycles (Damn, that Nokia is a tank!)

If 10% of the population went away, it would affect 1 & 2, but in any true practical lens, there's a ton of cheap empty houses, while on the other hand building repairable stuff that lasts or enough cheaply is where economies move to more complex technologies by saving time and effort in useless endeavour of debt chases or consumption-oriented wasteful productivity

Economies are built by rich people for rich people. A few million poor people dead doesn't really make a dent in them.