One of the most well documented facts about trading is many traders fail. Depending on the asset class, it's usually like 75-90 % of all market participants are net financial losers, with about 5-10 % making consistent great profits, and the rest breaking even or barely up or down...
Trading is an elite performance based activity, many are called, few are chosen. And you need to be prepared to outperform the vast majority of the population, if you want to make a prosperous living as a trader.
I think you're rather economic with the truth, because what you cited is an establish fact of life, known as Pareto principle and it is something that cuts across every area of life and not just trading. It's exactly for the same reason that 75 - 90% of the wealth of the world is in the hands of 5 - 8% of nations.
Good news, however is that anyone can aspire and determine to be within the 5 - 10%, champions are made not born!