I don't think many people seriously believed voting itself was hacked.
Actually 50% of Clinton voters believe that, or about a quarter of the US population. Of course Trump voters had their own preferred conspiracy theories as you can see from the same report. What it shows is that people believe the narrative of their preferred news sources, and that neither major party is immune.
Rolling Stone has a nice article with an overview of the whole situation and why we should be skeptical. It's nice to see that coming from them, because MSNBC won't say it (gotta support out side) and nobody is going to believe Fox saying it, and sadly the rest of the press is starting to fall in line with one side or the other.