It's fine to say "prices go up when people buy" - we know that - I think the question we're trying to figure out is whether it's priced in line with comparables in a way that it would at least hold its value moving forward.

This sounds like a tautology. Is it literally impossible for the stock market to ever be irrational? Even if the stock price has gone down $250 per share in the past year?

Within the game, "the stock market," it is rational. The game is "What do I think other people will pay for this?"

The price of a given stock is always rational under that game.

Your problem is assuming the price is justified based on any particular aspect of any company in question. The answer is almost never "Yes." The price doesn't represent competence, it reflects confidence.

The market is a confidence game, and so the prices are always rational. The game itself is even rational! However, the actors are not always or often rational, and prices are only ever coincidentally (and rarely) aligned with the actual value.

The price going up that much in that short of a time period is very rational, because the price is a function of what others think others are willing to pay for it, rather than trying to reflect anything wider.

I disagree with your definition of rationality, and I find it a bit bizarre that a group of people acting irrationally, as you admit, can magically become collectively rational... except "by definition", i.e., your definition.

Is there anything special about the guy? No, it's just that stuff becomes viral.

Obama became viral in 2007 and Tesla/Musk became viral in 2020.

Don't be fooled by the analysts, prices, earning reports and numbers popping. At the end of the day the stock market is a popularity contest and thus it's subject to stuff going viral