New Delhi, Jan. 12 -- Billionaire investor Warren Buffett, who built Berkshire Hathaway's massive portfolio, thinks that some people should not own stocks and do "dumb things" when prices drop.

Speaking to CNBC in 2018, the Oracle of Omaha reasoned that the longer you hold a stock, the less risky it becomes, and that selling is a "dumb thing" to do when your stock price drops.

Commenting on percentage rise and fall of stock markets, the ace investors noted that stock price movements are "nothing" when comparing it with businesses that earn 12% on equity and reinvest, adding that the S&P, has "for decades, earned on tangible equities a lot more", which translates into more higher prices.

"The way people think about it (investing in equi...