In my opinion, "everybody" knows -- at least deep down most people know -- that Trump will most likely be a disaster as a president, but hope, partisanship, a lack of discernment, etc obscure the truth for many.
If you disagree with this, I'd be curious to know what you base your optimism on? What do you see in Trump that indicates to you he'd be at least a mediocre president, and not an outright disaster?
Haven't seen Democrats this upset since Lincoln freed the slaves...
I feel the scale of the President-type job is actually beyond any single individual, and because of that, it's more his cabinet and other office holders that are going to do the heavy lifting. I think the left should feel lucky that it's him, and not Pence who is the President; Trump is far more center/left-leaning verses other choices. He doesn't hate gay people, doesn't have crazy fundamentalist beliefs, and doesn't think it's his duty to empty your wallet. (Hi Bernie, and Obama!) Honestly, Hillary lost because she's not much different than Trump, but she has tons more scandalous baggage. The dems screwed themselves by screwing Bernie, clearly the more moral and useful candidate was snubbed.
There was no reason to believe the rookie senator from Illinois who had a high score streak for missing sessions was going to be a useful President, but everyone literally voted for him because he was black. This type of shill candidate will not work anymore we can share too much information and don't trust the media completely. Identity politics is not going to be good enough to get anyone elected these days, and as soon as you start with them you alienate someone else and shoot yourself in the foot. If you think Obama was a good candidate ever you already need to re-evaluate some life choices -- he was bad on paper from day one, and was up until the absolute last day of his term. If you think Hillary was ever a solid choice - you're nearly qualified as postal.
P.S. I really think Obama won specifically due to inferior Republican candidates, not that the the Bush Presidents we're any better. Everyone past Reagan was pretty much a fail, we just got a bit of air with Clinton (and I think he was LUCKY), and right back into the drink.