Largely because what the dems didn't realize is that even though Trump is disliked by a lot of people, the only people more universally despised were the dems. They are like that team you always hope gets obliterated because you hate their fans so much. The team itself you really don't fault, but the supporters are so arrogant, nasty, hate filled and nauseating you just can't wish any part of the organization success ever.
I think most the lefties living outside the USA are completely unaware of how many people loathe them.