In India, the trend of a big mass hero doing any film and it raking up big numbers is common. You have a mass hero in Tamil Nadu do a film, market it well and the opening numbers are very good. By the time the movie struggles to sustain, the makers recover more than enough money and label the movie a big hit. This happens in Bollywood too. A Salman or a Shahrukh or an Aamir film easily touches 100 crores. If they make a masala film, its cheaper to make them and so they make profits very easily irrespective of the content of the film. Jab Tak Hai Jaan which was criticised made 100+ crores. And its budget was just 50-70 odd crores. Dabaang 2 was a horrible film, and it was a 100+ crore superhit.
Not at all healthy for the industry. Fan worship is seriously making bad movies run well. And big stars take the easy route of satisfying the fans and end up making mediocre products. Thuppaki and Mankatha were exceptions though, and were good films that became big hits.
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Rajesh and Santhanam. And also Karthi to an extent. The guy's lost his head (same with his brother too) and is making crap masala films instead of waiting for good scripts like Paruthiveeran, Naan Mahaan Alla, Aayirathil Oruvan, etc. Both Karthi and Surya are going down the wrong path and will burn themselves pretty badly for sure.