I would word it differently but I agree that finding that "positive expectation" is simply a very hard thing to do.
Quote from 1a2b3cppp:
There reason there are so many failed traders is because no one has a winning system.
People blame it on other things, like gambling (which admittedly, some people do treat it as), or poor discipline, and that may be true, but even perfect discipline only works if you have a profitable system, and almost no one does.
I believe last time this argument was made, someone replied with "no, it's discipline. There are tons of profitable systems out there, people just can't follow them." LOLOLOLOLOLOLOLOLOLOLOLOLOL!!!