We are.

What I was trying to get across was more fundamental and perhaps pedantic.

There is an actual, real life mechanism that determines the price. There are people asking for a price and other people bidding at a different price. Each one of them is slightly nuts and/or reasonable in their own special way. The stock market valuation of a company is only accurate if their collective behaviour averages out and counterbalances all their individual errors.

For example, a seller sells a few shares of a stock because they need the money for a vacation. That has no bearing at all on the true intrinsic valuation of the company. But luckily there are 9,999 other buyers and sellers whose transactions - on the whole - average out his "irrational" sale. There is one lucky buyer who got some stock for a slightly lower price than he normally would have...

And the market is only accurate if these people, as a whole, show no collective bias that skews their average price to an inaccurate value. For example, if everyone thinks "oil is good, nuclear is bad", then oil companies will be slightly overpriced and nuclear reactor companies will be slightly underpriced.

Market demand determines the price, ...

This assumes that there is a sufficient volume of recent transactions that average out any errors in the valuation. So that's why I said "If there are no buyers... etc."