as someone who has written books ... essays like this can be both mostly correct, and an excuse not to finish your next book, put it on the market, and keep it on the market until sold. So beware them!
For some it will mean they won't write. For others it will mean that they adapt to try to bring down the investment and increase the chance of success. E.g. submitting shorter works to magazines or taking editing or smaller writing jobs are both far more likely to pay off, and far lower investment.
But if you're working on a novel because you want to write, then you should ignore the numbers in the article and write anyway, and see it as a sobering view of how little it takes to be a relative success as a writer. E.g. you're already doing better than most once you're selling in the low thousands, even if that isn't paying the bills.