I personally think there is a difference between a full time investor investing to make a living and someone who already has a lot of money and let others do the investing for him/her (AKA High Networth jobless individual with investment returns). I think all of us are trying to become the latter at some point in our life
Relying purely on investing to make ends meet is risky from the examples I've seen around me. But from the examples I've seen :
Networth : The "investors" type generally have networth above 3 million SGD, most of them achieve through inheritance or selling their company. The "traders" type I know have an investment amount around 300k.. highly unstable annualized returns. I don't have the whole picture and I believe many of them are highly leveraged in their positions.
Gains : 8% annualized is too high compare to the figures I've heard. Its more like 3~5% for "investors" (Of course they can get higher gain by leveraging their positions)... while "Traders" varies greatly.
Outcome : For the past 6 years I've heard 4 bankruptcy cases of such people, all due to being too leveraged in their positions and were caught when the market suddenly change side.