It's not even Trump... it's the group of far-right and ultra-conservative people and businesses in the background, who will shape the US for years, maybe even decades to come through the pipeline that is Trump and the GOP. The first term was already a shitshow, where they already caused a lot of problems for the future of the US, but were also held back by the chaos and bizarreness of the whole situation. Plus too many people realized too late that he would actually win it and then they couldn't be sure how it all will go down.
Now though... the people and businesses in the background know exactly what they can do and could "achieve", if the second term ends up happening. This is going the be way, way worse than the first term.