Is that he reduces his losses.
In essence, it's difficult to overcome a loss. So, he buys companies that have a strong "moat" of protection, confident customer base and brand that have good return on investment. That investment is piled back into the business or via dividends, into other businesses which do the same.
Thus capitalizing on the power of compounding to...
He built a giant snowball going down hill. His nack at valuing, identifying trustworthy and skilled management, and following investement discipline ensured success.