"you can make a pretty good living trading stocks short term." Academic studies don't support that.....uhh, thats pretty silly. Academic studies look at 'the average investor'. If you are a professional investor with knowledge, experience, know how and an aptitude for trading, of course you can make money. There are thousands of people working for brokerage houses throughout the world that make great livings.
Again, sure, if you are an average Joe without years of knowledge, education and experience, you wont do all that well trading. Just like if you are an average Joe who decides he wants to be a movie director, so he watches a bunch of movies, takes a course at a community college....that guy probably wont be able to make money as a movie director. Yet there are a bunch of people who make money as movie directing motion pictures.