It's just slot machines with a more respectable coat of paint.
Is there absolutely no skill or expertise involved in it? I don't know because I haven't spent too much time studying it, but it seems a lot more like poker than slot machines. People who are better at the game should have an edge on others.
In poker it's possible to be enough better than the competition that your advantage is obvious (to people who are similarly skilled, at least). I'm not sure that's the case with day trading.