You're right, but it's important to remember that the Left always overreacts like this when the Right takes power. A lot of anons are probably old enough to remember the Bush years, and in a similar way, he was portrayed as an idiotic man-child incapable of doing anything, and yet at the same time, an evil, existential threat to the nation. Marvel has been demonizing Republican presidents at least as far back as Nixon (and that infamous Captain America story even started before Watergate happened).
It's not that the Right don't react the same when the Left are in power, the difference is that they don't have the media and entertainment industry on their side, so you don't get to see their impotent rage at losing unless you go looking for it. It's not omnipresent in movies, television, comics, music, etc, the way it is when the Left loses.
It does feel like a lot of the outrage over Trump is less about anything he's done, or wants to do, and more about what he represents, the push-back against their "progressive" ideology, also how they thought they were on the brink of permanent victory, and hadn't even considered the possibility of losing.