"After '3 Idiots', spending five years directing this movie was madness and passion, there is no logic in it. It could have turned either way but I am happy that people like James Cameron and Alfonso Cuaron have praised it," Chopra told PTI.
"I come from Hindi medium and at 62, I unlearnt everything to make this film."
Amitabh Bachchan and Aamir Khan launched the trailer of the movie which is set against the backdrop of US-Mexico border gang wars. It releases globally on April 10.
The film has an international star cast in "Full Metal Jacket" star Vincent D'Onofrio, "Star Trek" actor Anton Yelchin, Chris Marquette and Maria Valverde.
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The director-producer, whose filmography includes "Parinda", '1942: A Love Story", "Eklavya: The Royal Guard" besides the "Munnabhai" series, "3 Idiots" and "PK", said he knew he had a good script and that gave him courage to follow his dream.
He, however, rubbished that the movie was a remake of "Parinda" saying reworking the same story would have been boring for him.
"I am not driven by money. I am in films because this is what I love to do. This is why my movies don't replicate each other.