In essence, failure occurs when we give up and stop trying. Isn't that what you mean, OP? I also agree with this opinion. Those who fail are those who can't continue. The reasons can be numerous, but that's the path to success, and that's why successful people, especially in trading, are a minority.
By the way, I disagree with your opinion about "trading being a matter of luck." It's not gambling. While luck is sometimes needed, most trading requires skill and knowledge to generate profits, and that's why we must always keep learning.