He's not an idiot because he's a capitalist. It's that capitalism encourages the idiotic type to try shit out, because those are the ones with most self-confidence. They're mostly also the least likely to really consider the responsibilities such as: your employees depend on you now, if you fuck up majorly, you'll screw over all your employees' lives, potentially their families too, potentially irreversibly

So yea, the function of "CEO" naturally attracts cretins.

And God forbid such a moron's business becomes even slightly successful, because guess who suddenly feels smarter, less accountable for his terrible character flaws and toxic behavior? That's right. Usually, businesses which make it are mostly just lucky. But you can't explain this to cpt douchebag, he thinks he's magically smarter and better at life than anyone.

And the better the company does, the more the Boss will indulge in his dysfunction and craziness.

That's why, statistically bosses are highly probable to be the scourge of humanity. It's not just capitalism. it's just the toxic mix of luck, power and stupidity - all three combined with whichever the boss' character flaws and weaknesses are. Only in capitalism, power usually takes the form of money, that's all. But the issue is even deeper with people.

(i hate capitalism too, but I think blaming it all on capitalism and calling it a day isn't gonna address such a fundamental issue with people. I come from an ex communist country and that shit is just equally toxic if brought to it's extreme version - and for the same reasons to do with the human psyche too.)