Given the fact that Snowden knew the pervasiveness of the NSA spying programs, I'm guessing he knew that it wouldn't have been hard for the government to deduce

Given the fact that Snowden knew the pervasiveness of the NSA spying programs, I'm guessing he knew that it wouldn't have been hard for the government to deduce that he was the leaker eventually. Plus, it was pretty likely the government kept track of its workers in a way that would have made it even easier to identify the leaker eventually. So he probably decided to just cut to the publicity part to protect himself. In either case, you don't really know he was in it for fame.