You're describing the difference between macroeconomics and microeconomics. Pretty much every successful entrepreneur I know has a very solid grasp of microeconomics, oftentimes much more solid than most economists or financiers. They don't always have a detailed understanding of macroeconomics, and many of them don't need one to run their businesses.

When you can steal market share from existing incumbents, oftentimes with a 10x better product value proposition, then currency, interest rates, and consumer credit are rounding error. They don't matter - you have a potential market that is many times greater than the current size of your company, so you just convince your competitors' customers to switch to you and you get growth even if the economy as a whole is contracting. But on a macro-level, this is zero-sum, because your gain is your competitor's loss. On a macro-level, the only things that lead to everyone's gain are improvements in productivity and better use of unemployed resources.

Now, when it comes to the original thread subject, this is very relevant: it's worrisome that Trump seems to be treating the U.S. economy as a whole the way you would treat a business, and is applying microeconomics tools in a situation subject to macroeconomics. But it's not true that Elon, Zuck, etc. don't understand economics; rather, they understand economics, but the part of it that is relevant to their daily lives is different from the part that pundits and economists care about.