A number of reasons. For one, the only proven, verifiable way to profit long-term is insider trading. Which basically means it's a con game whereby those in power fleece those without. For another, I've seen nothing destroy a company faster than "shareholder concerns." It isn't an "always" thing, but it's a lot harder to execute long-term planning when you're beholden to quarterly earnings reports.

I've also never been close (working for or friends with those working for) to a company whose stock price had anything to do with that company's performance or viability. The most striking example for me was when I asked a buddy who worked for Real Networks how his stock was doing: "We're down five percent. It's amazing, really - we released a report yesterday that not only beat our earnings estimates, but actually declared a dividend. We're one of the only profitable dot coms out there. But because our numbers didn't beat moody's, we're down twenty bucks."

So really, you've got a distracting game that exists to fleece fools. If Wall Street had to follow the same basic rules as Vegas, I'd be a lot cooler with it.