If you think so, you should explain where exactly the 1.624 trillions $ value of Google is, given that its net assets are about 267 billions $ and they had about 118 billions $ in cash (or cash equivalent)

You can sell a cow for $1000 on the meat market. Or you can keep that cow, so that it produces milk for many years and earns you a total of $5000. This is the difference between net asset value and valuation. If you were to buy a cow, and producing a cow was next to impossible (cows are one of a kind, like unicorns), then the price of the cow would be closer to the valuation than its net asset value.

Only thing is the 5000$ are what you are hoping to get, not what you have. If you sell the cow to another farmer you will get less then 1000 $ (or maybe a little more), only a fool would pay you 5000$. Obviously I know there are some exceptions, but this is the normal situation.

YouTube would exist almost as a hobbyist site that has issues scaling its users and monetizing its activity.

This is because YouTube is something that people can do without. But there is no technical reasons why a paid service should have scaling issues. In the real world there are a lot of paid service that scale pretty well without any issue.

At some point it would have failed because people would find it frustrating to face the lags, and the owners (who by the way are still owners, who still invested in it, so actually very little changes in this mechanic) would introduce subscription fees or something in order to use the platform. Would it have become a ubiquitous platform as it exists today? Would you have it on your tablet, tv, phone?

If people would find the service worth enough then people would pay the service. The boom of Netflix is an example: as long as people find it worth the price, they happily pay it. Once the service is not worth anymore (or not seen as worth), people stopped paying.

Probably not, but any of its competitors would have gone on a very similar journey and you’d be complaining about a different company, because you need investments in order to grow, become better, more attractive, and become both the way that people choose to upload content, and the way that people choose to consume content. And it would have been YouTube who couldn’t have afforded to keep the lights on at this moment.

If a competitor had come out with a better service that was worth it, people would have paid it. Again, Netflix is an example. Only difference is Netflix also had to pay for distribution licenses and to produce shows, which add up other problems. Another example is Patreon: people pay to access things that they value worth the price.

If you’re suggesting that the entire stock market rests on the “greater fool” principle, then maybe you don’t know about the end goal?

Well, looking to how all the big stock exanges scaldals ends, I would say that there is nothing that make me thing that this is false.