Why didn't Kryptonians leave Krypton inorder to survive ?

                             

         Ever since you watched "Man of Steel",have you ever wondered why the people of Krypton just stayed on their planet till it's core became unstable and blew up ? One version of the tale states that the kryptonians had exhausted their natural resources too much to the level that space exploration was banned.The Kryptonians have either emptied their energy lot or stayed lazy like it wasn't a threat until one day the planet went kaboom.In another version it is stated that, the kryptonians were genetically bonded
to their home planet,Krypton.The genetic bonding caused severe pain and death to those who tried to escape the planet.Now this might sound crazy.A advanced species trapped to a single planet.But if it was the case,how did Superman escape Krypton ? Why didn't superman die if Kryptonians are genetically bonded to Krypton ? .First of all,Jor-El (father of Superman,Kal-El) and a handful of people knew that the yellow sun is capable of energizing Kryptonians,but by that time,Space Exploration was banned.By merely attaching a warp engine to the birth matrix,Kal-El was "born" when the birthing matrix opened on Earth.