I think you stand to make more money (perhaps lose more as well) by investing in individual stocks. I don’t know a good way about it, except to dump some money in there as wisely as possible, consider it a total loss, and learn by doing.
Sorry totally misread the question. Yes, I think most people play the market on the side of a full-time job. You have to consider your investments as long-term investments to do this as you cannot monitor all the intricacies of day-to-day market flux while working full-time doing something else. But in the long run, I think people have calculated that you come out ahead and that it is the only surefire way to beat inflation.