Borrow, borrow borrow.
Talking about hedgies, FT said (emphasis mine)
These include asset prices moving in long-running trends, cheap stocks performing better than expensive ones, stocks with stronger finances outperforming weaker ones and the ability to borrow cheaply and invest in higher-yielding assets.
Of course Buffett doesn’t do this but he has the premiums from his insurance co to play with. Others have tried to play this game with distarious effects. Recent example is Anbang. Another long forgotten example is FAI. When I was a newbie in stock broking (in Oz), Larry Adler was a corporate raider using the float from his insurance co. After his death in 1988, FAI got into very serious trouble, that could be traced back to his activities.