What Democrats and some Republicans hate about Trump is they have no control over him. Washington is like a club. Sure, they scream and yell at each other, but at the end of the day, they are in the same bar buying each other drinks.
In this club you don't barge in the back door and take the highest seat in the land. You need permission from the other club members. You have to work your way up from city council, to state rep, to Governor or Congress. You have to scratch backs and have yours scratched as well so they have something on you if you decide to get out of line.
Trump came in owing nobody any favors. They had nothing substantial on him. Everything they harassed him over was all made up. In spite of that Trump kept on moving forward with his successful ideas no matter how many people he pissed off.
That's why they hate him and continue to try and stop him with more petty bullshit.