You had to be genuinely gullible to vote for Trump this time, but that wasn't the case in 2016. I'm thinking of the blue-collar union members who voted for the Trump '24 ticket, for example, bitching to everybody who would listen about the price of eggs under Biden. In 2014 they would have been dragging down the Democrats' collective IQ, and now they've switched sides. Yet I wouldn't be surprised if many of them are still registered Democrats.
It seems like he's mostly doing what his coalition was hoping he would do? Certainly to a greater degree than in 2016. I have not seen any credible indications of post-election regret from his coalition.
They believed that things were bad and that Trump would make them better rather than worse. If that's not gullibility, I don't know what is.
His voters will ultimately be among his greatest victims... but he'll blame Biden for whatever goes wrong, and they'll lap it up like a dog with a dish of antifreeze, just like they always do.