Let's take Facebook, where I think Mark Zuckerberg has ~60% of the shares, and only 40% are on the market, thus even if you buy them all you cannot gain control of the company. You can't extract value from the company from this avenue.

Again, what gives inherent value to a stock is that you, or someone else, will be able at some point to get value from the company itself, not from someone else. In a rational market, a price rise should mean the market will eventually be able to extract more value from the company then thought.

Let's take a planet in another galaxy. I would argue the inherent economic value of this planet for a human on Earth is null. You cannot and there's no realistic time frame in which you would be able to extract value from owning it. And yet you could sell the ownership, lend it, ..., and make money. That doesn't give inherent value to the planet, it's just speculation.