The actor and producer reportedly refused to promote the film after its release.
He told Mumbai Mirror: "After a film releases, its success no longer stays in the hands of the actors or the makers. Whether you put 30, 25 or five days into the promotional activities, the audience takes the film's fate out of your hands.
"I remember vividly, not so long ago, I had gone all out for the promotions of a film. I spent time away from family, not to mention losing sleep and putting my other schedules on hold. But the audience had already made up their mind.
"This time, I let the film speak for itself, that's all. I believe, if it was destined to be a blockbuster, it would have been. Regardless of my actions," he added.
Joker director Shirish Kunder has now been dropped from Kumar's upcoming production Kick.
Co-star Alex O'Nell revealed last week that several comic scenes were cut by Kunder because they were too "English-heavy".
Watch the trailer for Joker below: