Snowden was a dude that was just an average government employee. He was set. Just show up and fill a seat. Collect the checks. Take your sick days. Vacation at Disney one week in the fall and Deep Creek Lake one week in spring. Rinse and repeat for a while then draw that federal employee pension.
But he saw things that disturbed him. Obama's war in Afghanistan broke laws - a lot of laws and a lot of times. He decided that people needed to know but knew his superiors were aware of the wrongdoing and that higher-up in legal claimed what they were doing was ok.
So he made a choice - one that would never allow him to see his parents again and keep him living on the run - maybe for the rest of his life. The Feds still consider him a "traitor" for exposing their crimes and their crimes were never prosecuted.
This Documentary captures the story as it happened.