" it just appears to boil down to a numbers and sentiment game that doesn't seem to be a rational way to determine a company's "real" value at any given point in time"

The interesting question is "What makes this important to you?"

I ask because there is absolutely a rational way to determine a company's value, it involves analyzing its market, its product, its ability to grow and develop and the its ability to stay ahead of others who would try to do the same thing.

Putting the world "real" in scare quotes suggests that there is a large difference between a value that you came up with internally and the one being exhibited on the stock market today. This isn't a whole lot different than the 'SnapChat is worthless' discussion of a few days ago. It also isn't surprising since different people value things in different ways. But it is important to recognize that you are not wrong, if it is worthless to you, it is. And that is just as valid an assesment of the company as one that thinks it's the best thing since the wheel.

So why is it important?

When I was 8, I was selling some baseball cards at our yardsale, priced per their trade book value. At the end of the day, I was distraught because the only offers I got were well below the cards' value. The response from my mom still resonates to this day:

"Things are only worth what people are willing to pay"

The only way you can ascribe value is from the point of view any one particular entity (including yourself) at any one particular time. The only way you can see it is when a transaction takes place.

There's nothing wrong with stock markets conceptually, and there are indeed some which are nicely regulated and quite fair.