I think everyone expected him to cry fowl when he lost in 2020. I think being a little surprised that he'd go so far as to stage a violent coup is probably understandable.
Figuratively, though. It wouldn’t be difficult to imagine Trump squawking like a chicken and flapping his arms while turning in a tight circle when something truly upsetting to him occurred.
I can say that it was not the only reason. (After all, he did lose the 2020 election) In 2016, I voted for Trump. This was because my friends did too. I thought he was going to drain the swamp so to speak. He had very good slogans and populist policies that appealed to the masses. He made you feel seen.
This changed when he kept on with his attempted Muslim ban, rhetoric to lock people up, and name calling throughout the first three years. There were some bright spots, such as better finding to CBP and policy changes to alleviate our court system (still not perfect as one needs more resources in the court system too) The Trump administration actually engaged over in Central Asia which had a noticeable impact over there. My dad had pointed out that the Government was doing some good work not quite making it to the mainstream media. I noticed Britain leave the EU for questionable reasons because of the same forces. I read the Mueller Report on Russian interference in the 2016 election (and barely remember it four years later)
I thought that it was likely that the Russians colluded with the Republicans, but it could not be proven. And it could have remained that way if not for Trump's first impeachment. Trump withheld aid to Ukraine in return for finding dirt on his political rival Joe Biden as well as trying to pin the election interference on Ukraine. This impeachment had a man I highly respect break from his own party and vote to convict for abuse of power. But he was the only one who would stand against the tide.
Three years in, I could be counted as a swing voter, favoring neither party. I had seen the Republican party pay lip service to Christian values and yet fail to have integrity. I had a mild dislike of Trump and was starting to think his policies were not implemented correctly. Then Covid happened
I lost my job, was chronically online, and listened to a lot of podcasts. Trump had a really bad messaging problem then. I thought he needed to throw his phone in the toilet and stay off of Twitter. He recommended hydroxycloroquine as a treatment which was kind of dumb. He didn't support his governors when they would lock down states for public health and instead would berate my own governor for trying to save lives. The more extreme Michigan Republicans would compare her to Hitler (Godwin's law at work) and Trump would engage with that. This mostly made me appreciate Governor Whitmer more as she was making good policy decisions.
A couple months go by and George Floyd was killed by police officers in Minneapolis. This was murder. People would be protesting the police brutality that pervades police departments everywhere. The police unions that let problematic officers go from one police department to another and spread their often racist policies. There were protests everywhere from DC to Seattle. While many conservatives will focus on the shit show that was CHAZ, I saw the one in DC. Especially on one morning when security services cleared the park for Donald J Trump to go across the street for a photo op. This photo op was front of a church where he held a Bible upside down. And in that moment, I saw the Trump presidency as a fake Christian presidency. It didn't matter how pro-life he was or how many pastors endorsed him anymore. That ruined it forever for me.
The following months would only serve to cement that opinion as I saw him lay the groundwork for denying the election by discrediting mail in voting, especially as there was much more need of it than previous elections. I thought this was a stupid move as he would be undermining Democratic legitimacy. Little did I know, that was the point. We all know what happens next though. The election happens, Trump is defeated, launches over 50 lawsuits, wins one, and changes zero districts. He incites a riot at the Capitol. He spreads conspiracy theories. He blackmails a secretary of state. He gets impeached again and gets acquitted again.