Others have commented things to the effect of "they thought they could get away with it", which I think is partially true.

I do wonder if there's an additional element to this.

Perhaps they just got impatient with their slow communist take-over of the country.

Or, perhaps, they viewed Trump (in the White House), as an existential threat to their plans (i.e., The Great Reset), so, he had to go, no matter what. I suspect this played a large role.

On that note, Curtis Bowers talks about the threat of Trump to their agenda in this episode of his weekly podcast:

https://www.youtube.com/watch?v=S-f-ACfdnnI