“The Atlantic” has a cover story calling for Trump’s impeachment written by Anne Applebaum. She is a notorious proponent of using American blood and treasure “to make the world safe for democracy”. Tweets like this form Trump is the main motivation Applebaum wants to eliminate Trump.
The US political establishment allows debate and disagreement on a whole range of social and economic issues. You can argue for high or low taxes, for or against some environmental regulation, for or against gun control or access to abortions, etc and still stay in relatively good graces in the eyes of the elite, or at least have the unqualified support of your own party. What you CANNOT do is challenge the elite's consensus on three issues:
1. Unlimited mass immigration from the Third World is a great thing socially and economically.
2. The purpose of the US military is to act as peacekeeper in ethnic/tribal/sectarian conflicts around the world and to nation-build afterwards.
3. Our trade policy should make it as easy as possible to offshore and outsource.
Trump's big "mistake" was disagreeing with the elite establishment on all three of these issues, which is why they're out for his blood in a way that they never were for any other President. It also explains why Trump's own party often doesn't have his back either.