In my experience you lose 5% with a probability of 99% and make 100% with a probability of 1% giving you an expected value of less than 0. It's not about understanding assymetry, it's about finding mispriced securities which is far harder for us mere mortals than you let on (I'm purposely goading you to provide such an example, if it isn't obvious!)
No, we are in agreement there. I have always asserted that trading in general is very challenging. Even simply investing is challenging. Getting involved in things like optimizing asymmetric payoffs is something that should not be done by mom and pop types (most of ET). I do lots of these trades and have no desire to discuss them so feel free to discount that how you wish. I do agree that most people should just buy and hold an ETF like SPY and call it a life. They would far outperform most of the junk I see on ET that gets espoused as a trading strategy.