There are quite a few traders who made a billion largely through trading. But it gets to a point their money is too large to trade and they have to diversify to real estate or something else.
Go to the FundSeeder site to see what the top 50 armature traders are doing. Markets can be unpredictable, even illogical at times but they have phases, if you got a strategy that works within the current phase, 600%pa on position val is normal (higher, up to 12,000% on capital, if you leverage x20). Returns of that magnitude will continue until they don't. What I mean is that such returns contain high risk and are not sustainable... once markets enter a new phase, the strategy no longer works and you end up being one of those guys that is a millionaire one day and broke the next. Once you been trading long enough to have gone through all the phases and have developed a strategy that works in all market conditions then your highest expectation is to double your money every 3 months. i.e. you practice proper risk management and proper risk/rewards strategies. These somewhat limit your potential rewards but also limit your risk giving you a sustainable average return. Within the current phase of continual new highs, it's easy to make the returns you are experiencing but take care, conditions will change without warning.... making money under all market conditions is more difficult than you might think. The total market cap of the S&P500 is currently at 183% of GDP with a PE of 40% above the 10 year average. These are not normal conditions, a return to normality has to be factored into your trading strategy.