90% if success of failure in trading/investing is related to psychology, human emotions and discipline.
Even investors who simply buy an index fund or a mutual fund will have very different results, depending on how they do it.
Here are some articles that might help:
Probability Vs. Certainty Trap
Are You EMOTIONALLY Ready To Lose?
Are You Ready For The Learning Curve?
Why Retail Investors Lose Money In The Stock Market
Why Simple Isn’t Easy
Thinking In Terms Of Decades
Can you double your account every six months?
Is Timeframe Your Biggest Mistake?
Are You Following "Tharp Think" Rules?
Top 10 Mistakes New Option Traders Make
Price Of Options Trading Education
How To Become A More Profitable Trader
5 Stages Traders Go Through
10 Fatal Mistakes Traders Make
Learning To Win By Learning To Lose
How To Avoid Emotional Mistakes In Trading
10,000 Hours Of Trading
Bitcoin: The Greater Fool Theory?
Investor Discipline Is The Key To Success
Buy High, Sell Low: Why Investors Fail
How To Control Losses And Protect Profits
10 Tips: Trade Options Like A Pro And Keep Your Day Job