Filmmaker Ram Gopal Varma, quoting his writer-actor Neeraj Vohra, once explained to me how box-office really works.

The numbers obviously tell you how many people watched a film in a theatre. Hum Aapke Hain Koun (HAHK; 1994), starring Salman Khan, for instance, was the biggest money spinner ever in the early '90s. Hum Saath Saath Hain (1999), a film with the same hero, director, producer, genre, on the other hand, saw its audiences hugely eroded. Why? Because ticket receipts don't tell you how many of those people actually loved the film! The sequel does.