A winner's reasoning could be completely unrelated to the event at hand and we'd never know the difference. A loser's reasoning is definitely wrong in some way, so we can learn something from it.
In markets the loser’s reasoning often comes down to poor timing. They see similar red flags but can’t quite catch the right time. Predicting markets is relatively straightforward, predicting when something will happen is infinitely harder :)
In reality, it's about picking a position that one can hold through various trajectories and that is profitable in most of the more likely ones. If one has assessed the actual trajectory at a lower probability than reasonable, that's still something we can learn from.
You can be right 99% of the time and still lose money because the market always rewards based on risk. Conversely you can be right 30% of the time and make billions.
With market timing you don't need to predict the instant something will happen, your time horizon really should depend on what your drawdown is. The predictions don't have to be single events, it can be a market environment. Timing a bear market when everyone is bullish, etc...
Every time you short the market you effectively open yourself to infinite loss, whether you are leveraged or not. There are effective hedging strategies in place, but unless you're doing this for a living or a very serious hobby, its tough to figure all the pieces out. That is why staying on the buy side can be pretty helpful for not losing one's shirt.