Ignorance is a cause of addiction but it is not the only cause and not all trading addicts don't understand trading. There are many people who know the risks and consequences of overtrading but they still continue to trade and the reason could be because they cannot control their emotions.
Like gambling addicts, no one understands the harmful effects of gambling better than them and they always advise people to stay away from gambling, but they cannot stop gambling. Obviously their addiction is not due to lack of knowledge but may be due to psychology, environment...
It all depends on the person, possibly on their character and their ability to be consistent. I have also noticed that those who can achieve some positive results in gambling are often able to achieve the same in trading. And I think such people are consistent in everything. What I mean is that if they were less disciplined compared to others when starting some business, I believe these people would have better results in business. In other words, I want to say that the approach matters a lot. If you take a thorough approach to any endeavor, there is a high chance you will be successful.