Can't hold on, should we sell and cut losses?

Retail investors use patience to win over full time traders with good analytical skills and math calculation on cost and profit.
Warren Buffett saying "Rule 1 don't lose money and Rule 2 don't forget Rule 1". Risk management and psychological management are both as important as trading strategy to survive in bullish and bearish cycles.
As a newbie, I prevent "one round game over" to lose most capital before surviving a full cycle of bullish and beari...