How did Trump imagine he could stage a coup and get away with it?

Because for four whole years, he got away with everything.

Each time he got away with something, he escalated faster.

At first, he was afraid to fire Sessions - they warned he'd be impeached. Then he did. Nothing happened.

Fired an inspector general. Nothing happened. So he fired several more.

Couldn't get his loyalists approved for agency leaderships, so he put them in illegally. Court ruled it was illegal. But no one stopped him.

Couldn't get funding for the wall, so took it from the military, giving Putin a gift in the process. Ruled illegal. But no one stopped him

Refused witnesses & documents for Congressional Oversight. No one stopped him.

Refused to abide by court decisions regarding immigration & children stolen from their parents. No one stopped him.

Extorted Ukraine to get election help in the form of fake investigation of Biden. Got impeached, but GOP Senate made it clear from Day 1 they'd never remove him. So he kept on extorting to get what he wanted.

Every time he lied, agencies simply rushed in to explain or pretend like they agreed.

All those independent agencies - CDC, Homeland Security, even the weather service - were willing to withhold or even alter documents for him.

So, yeah, he thought he could stage a coup & remain in office.

Why wouldn't he? No one had ever once stopped him before.

They would warn him not to do it, he'd do it, and nothing ever happened.