Righteous Kill

why did deniro and pacino do righteous kill? i know it paid well, but really?
did they really think the script was good? the plot consisted of two 70 year old men chasing down a serial killing cop. there is three to four scenes of these two grandpas pumping iron and doing crunches and by the way pacino is a chess champion. why would they make this horrible film?
Sometimes work gets thin but the bills get thicker. I think a script were they help capture a criminal would have been better (old retired detectives who do the brain work while younger detectives do the work). Then have a real witty writing punch up some funny and memeorable lines for them both. Kind of like Morgan Freeman in Se7en (but they’d be at their homes, cafe with the younger detectives, etc.). Just older, world-weary detectives who’ve seen it all but get involved in a case that they really want to solve.
Righteous Kill