Yeah, that's Marx's Labor Theory of Value. The problem is that it doesn't account for the value of risk. It's easy to look at companies making money and assume they're extracting value if you ignore all the failed attempts that outnumber the successes 5 to 1. Now, rent-seeking is still a problem and corporations are often guilty of it, but the idea that all profit is rent is ridiculous. Some of it is compensation for risk.