Take a look at Les Misérables. The film is goes south very quickly at the end.
After Jean Valjean becomes wealthy why did he become mayor? He was still a wanted man after all. That was a stupid risk to take.
Why after escaping and saving Cosette why did he still stay in France? He seemed to have access to much wealth so why not go to Spain, Germany, Italy, Switzerland, or Canada? I mean how stupid was this man?
Simple... It would have made for a terrible story.
Most if not all the "errors" in Gravity were to make a good story.