No, he won because he bypassed the MSM, which the average American no longer trusts.

Why does a born-and-bred New Yorker, until then identified as a Democrat, and who obviously hasn't been paying attention to politics until now, doesn't read or use the Internet except twitter, isn't ideological but a pragmatist, suddenly go alt-right and hire Bannon, which he probably had never heard of until recently?

Because all he cares about is winning and being popular, and making money is a sign of being a winner and popular. And he sees the MSM is going bankrupt, as people don't trust it anymore and move to alternative sources like Breitbart, making Bannon a milionaire. So he jumps on the bandwagon...