My 2c:
1. lack of edge; this includes starting with a viable edge which temporarily no longer works in the current market environment, or has been priced in by the market and will never work again.
2. poor risk management skills; even if you have a viable edge, if you do not have risk management skills you will fail; the math involved here is not rocket science
3 inadequate psychological makeup; doing the right thing when you are going through a tough streak; appears easy in hindsight, but it is difficult to do in real time.
1. lack of edge; this includes starting with a viable edge which temporarily no longer works in the current market environment, or has been priced in by the market and will never work again.
2. poor risk management skills; even if you have a viable edge, if you do not have risk management skills you will fail; the math involved here is not rocket science
3 inadequate psychological makeup; doing the right thing when you are going through a tough streak; appears easy in hindsight, but it is difficult to do in real time.