Warren Buffett.REUTERS/Jason ReedWarren Buffett is selling stocks because he's getting out at the market high, Paul Dietrich told BI.The Berkshire Hathaway CEO will pile back in once a crash or recession hits, the strategist said.Berkshire cashed in stocks like Apple last quarter, raising its cash pile to a record $189 billion.Warren Buffett is cashing in stocks like Apple because he knows the good times won't last — but he'll spend big once disaster strikes, a veteran strategist says."He is selling out of one of the most overvalued stock markets in history at the 'high' and once there is a serious correction or recession, I am sure he will, as he always does, start redeploying those assets back into the market at much lower prices," Paul Dietrich told Business Insider.B.