I've heard multiple times that the vast majority of day traders, sometimes given as "over 99%", lose money. What's a realistic number? For specificity, use a one year time-frame.
For example, here are references to two such claims:
Moreover, in the typical six month period, more than eight out of ten day traders lose money
Ninety-two percent of day traders trying to scalp loose money. Only eight percent are successful. Out of the eight percent, only two percent of the day trading public make money on a consistent basis. Why do 92 percent of day traders fail and what makes eight percent successful?