A strategy that guarantees profit is: gradually withdraw the principal after doubling the investment.
The key to this strategy is to minimize psychological burden, reduce emotional fluctuations, and help you remain more determined to continue holding. If the market price falls, since the principal has been recovered, the remaining portion is entirely profit; the difference between earning more or less is just a gap. If the market continues to rise, you still hold more than half of the assets and can continue to enjoy subsequent appreciation gains.