He was underpaid and underappreciated by a dirty capitalist pig who likened the construction of Jurassic Park, a scientific achievement on par with the Apollo Program, to a flea circus. So he decided to fix both problems by selling some embryos. Bit of a dick move, but he didn't deserve to die.
Ok, first of how do we know he was underpaid and underappreciated? In actuality he had a very important job there with security and was likely paid quite well. Its a bit more than just a dick move to steal embryos of dinosaurs that could potentially do untold amounts of damage on the world if they got into the wrong hands, all so he could profit. Not to mention hacking and screwing up his own security system leaving all of them, including children to almost certain death. Anyway, its just a film so chill. :'D