Most of the time people have no real clue what the companies they trade do. It doesn't really matter to them. That's not their job. All they are trying to do is take money away from others who bet on the other side from them. At some level, the market is not efficient, contrary to what some people believe, that the market has everything priced in automatically.
Someone is willing to pay the wrong price for a stock at some given point in time.
The most tangible justification for my deciding to do this for a living was how I interact with other people now. Getting up early is a bitch, but working from 8AM to 3PM isn't so bad. Once you're done, there's not really much you can do until the next day. You can trade pre-market or afterhours of course, but there's not really enough volume to play it yet, unless you're an ultra daytrader. And if you take into account the fact that mid-day, the market is usually pretty slow, that leaves two times a day when you really should be making money.