It has a tangible effect on the short term value of the company. Just like the affair. People all tend to have short term thinking. The price of the stock drops because of behavior, this is real... but it is also opportunity. While you sell, I buy. You lose out.

The underlying performance of the company does not change based off of random tweets. If Tesla is good enough to take over the entire automobile industry even the CEO pulling off his pants walking around in public is a separate issue to actual performance.