Leonardo DiCaprio said his 'biggest regret' in his career was turning down Mark Wahlberg's role in 'Boogie Nights,' which he called 'a masterpiece'

Leonardo DiCaprio has admitted that his biggest career "regret" is turning down Boogie Nights. Mark Wahlberg was ultimately cast as adult film star Dirk Diggler, which became his breakout role. DiCaprio previously explained that he had to pass on Boogie Nights because he'd already signed on to star in James Cameron's mega-hit Titanic alongside Kate Winslet.