I may get flack for this, but this tends to happen after the US media and political cycle runs it's course. I felt a similar thing with posts on here regarding the Iraq war, Snowden, Manning, Occupy Wallstreet etc. The media and establishment is very good at pushing through it's agenda and narrative, and many people get picked up along the way, even those who identify themselves as strong liberals.
The constant theme running throughout this primary cycle being that Bernie would get crushed in a general, that he's unelectable, that Trump would easily defeat him, that his policies are too forward thinking for the country, that his ideas would bankrupt the nation, that his policies would never make it through and are unrealistic, so they should just be ignored, that his socialist ties are too detrimental etc. Basically the majority of it based on fearmongering and assumption, rather than facts or merit, which is usually the case with these things. So many people siding a certain way not because they actually prefer the policies of a certain candidate, but because the other person's are safer, and because they've been conditioned in to thinking the alternative is too dangerous.
The way I look at it is that America had a chance to actually elect someone truly Liberal, someone who could actually shape America to veer properly left, and instead they've just picked someone who's more status quo and same old than anything else. But based off of everything that has been happening of late (with America faltering in many key areas over the last decade or two, and wealth inequality getting out of control), I can't say I'm surprised. I think corporate interests will simply continue to take centre stage, and allow the country to continuously peddle between this centrist right and far right political landscape.