Karl's entire "study" of capitalism was a single attempt to start a newspaper, which it failed after one edition. He failed the practical. He was so business-illiterate that couldn't even hold a job that paid a living wage and was supported by Engels. His writings weren't based on study, they were based on isolated theorizing.
"It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong."
--Richard P. Feynman