This applies to all entrepreneurial activity. Entrepreneurs can sweat and bleed profusely, yet have nothing to show at the end of the day. Those who love only the money but not the process of working for that money will most likely fail.
Commonsense says that the ROI of any business must be proportionate to risk involved. Stock trading is one of the most riskiest business in the world. It is far more risky, stressful and tedious than stock investments. (RIO per month NOT year) Not worth the effort < 10% Hobbyist > 10% to 20% Professional > 20% It is not wise to compare the stock trading to any other business in the world. Professional traders wont be surprised at the ranking above.
I agree partially, any business you start, if ill prepared and just like trading, going to have a long road of defeat. My constant failures in futures for several years I really learned about my weaknesses in self, really the gamut of evil thoughts rise, and yet being stubborn, didn't change, you come upon a moment where in my case submitted that I had weaknesses in concept and best for me to become systematic and learn to program. I never liked the process of trading, actually dislike manual trading, thought I use to do it only for the money, but lost that feeling long ago, I get off on percentages actually- and only mine. I like designing systems/businesses as my personal happiness and I like fixing systems or failing businesses for others. Once you have developed your own happiness, first few years aim should be over 100% cause you have figured out risk management, but at some point the numbers messes with you and maybe you start altering exposure, or what you are doing has volume limits. Those with huge Hedge funds, am sure bounces into volume limits and why they can't do better than S&P Index. The S&P Index does not have concerns with clients removing their funds for vacations, they afraid of new highs, more employees required or upgrade equipment, hedge funds actually have to do far greater returns to beat the Index. Don't want to be buying way too much of anything, otherwise take a killing getting out. And don't matter if you solo trader or hedge fund as all applies.