Really? Who on earth thought it would go any other way, especially with the stooges the PLP were pushing into the election?
Honestly, the circles I move in plenty of people thought it would go the other way. Not based on evidence but based on their personal beliefs. It's the same way Economist magazine hilariously predicted a few years back that Hollande would never be elected as French President because he was "too socialist". I read that, laughed and asked myself if any of the staff at Economist had actually met the French. But the problem wasn't lack of evidence or indicators, it was an inability to see other people's point of view. They simply couldn't understand it. So yes, I know people who have literally laughed very derisively at the idea of Corbyn because in their mind and in their social circles, socialism is a synonym for failure and unfettered capitalism is the cure for all ills. I'm actually with them on much of that but unlike them (apparently), I have actually read my history books.
I'm not surprised Corbyn won even despite the various dirty tricks that were pulled to try and stop him. Such as setting an arbitrary cut off date to stop new members of the Labour party voting for him. Many joined just so they could do that.