He has had the worst first year in office then any US president. Hell, even Lincoln had a better year and that is with half of the country seceding.
What makes his ineptitude even more remarkable is that Obama left him with a good situation. I mean you have to be really incompetent to have a sub 40 approval rating with a stable and growing economy.
It's not just that Trump is incompetent, he's also an asshole.
True, but you can be an asshole and be an effective president (ex. Lyndon Johnson).
Trump's biggest problem is that he is grossly incompetent. All of his problems start there, most voters would be willing to put up with him being an asshole and unprofessional if he was actually competent at his job.
Trump's incompetence is his waterloo. if the Mueller stuff doesn't amount to anything, this is what will finish him in 2020.