It is honestly mind boggling to me that Trump is a candidate in America, and that people who were hyped on Bernie are now considering him.
That sort of leap is just something I don't get.
I think it's mostly what they're prioritizing when they supported Sanders.
Purely anti-establishment types that seems to be a near-majority of the Republicans, a strong minority of Democrats, and a hefty amount of Independents, will vote Trump because he's the second-choice of non-inside-the-beltway candidates.
Others are simply ardent anti-Clintonians. Those who hate Hillary and wanted to stop her in the primaries before they had to consider voting against her in a general election, and will have to now anyways.
Some support Trump because he claims he'll re-negotiate the trade deals America has established over most of recent history and push a tariff-based economic agenda to somehow restore the economy to pre-1980's levels of non-Neoliberal globalism - good luck with that by the way - and that's something roughly similar to Sander's anti-globalist message. Both had success in the industrial heartland because of people's frustration with outsourcing and... essentially the modern economy. If that's your issue Democrat/Republican hasn't really mattered.
Though what percentage of these people - just like members of the Stop Trump-movement - will factor into the election is nebulous to say the least. Lots of Clinton supporters ended up voting for Obama in '08, despite vowing not to and Clinton will attempt
to persuade on-the-fence Sanders' supporters she's not the devil really or stopping Trump is just too important to not support her, and some people who claimed they'd never vote Trump will for much the same reason never vote anything but Republican despite what they've said and Trump will attempt
to placate their fears that he hasn't a goddamned clue what he's doing.
Most Americans, despite all manner of insults regarding them, in my experience just have regular check book and dinner table issues - they aren't looking towards revolution - they just want to know the sun will rise tomorrow and they'll be safe and their plans for the future won't crumble horribly beneath them. That's why Bush did so well in '04 but Obama won so extensively in '08 - in '04 the Republicans promised security at all costs while 9/11 was fresh in people's minds, in '08 they were in the epicentre of power during the collapse of much of their collective sense of their economic security and self-worth. Obama provided stability in 2012, and Mitt Romney failed to undermine that sense or offer much of a positive alternative to get around that - this is particularly obvious with regards to the Obamacare issue, lots of fervour against it from Republicans but not much as to what their practical alternative is.
I think this election is this -- Clinton is pretty much the Stephen Harper of the American Democratic Party, she's not personally popular (will never be) and fairly mechanical as a politician, but she sounds like she knows what she's talking about particularly within the heavily coded discourse of modern politics... and while that will turn off people and is far from passion-inflaming, when you're dealing with a fairly conservative country (Which America is) and not really facing a horrible economic downturn (Which America really isn't) or massive 9/11-esque tragedy evoking strong fears that pushes things towards hysterical radical agenda (which really hasn't happened, San Bernardino didn't really change America forever and something worse probably isn't on the horizon) people will vote for the comforting presence of a competent-seeming person whose not out to make waves. Every time Clinton claims she'll continue the Obama administration's policies and maintain the general status quo, she's appealing to that inclination, and every time she gives some dry policy answer, it reduces the perception that she's at all risky.
Trump, well, he has an uphill battle.