Donald J. Trump took his seat at the dining table in his triplex penthouse apartment atop Trump Tower on the last Sunday in September, alongside some of the most sought-after and wealthiest figures in the Republican Party.

There was Paul Singer, the billionaire hedge fund manager who finances Republican campaigns and pro-Israel causes, and Warren Stephens, the billionaire investment banker. Joining them were Betsy DeVos, the billionaire former education secretary under Mr. Trump, and her husband, Dick, as well as the billionaire Joe Ricketts and his son Todd.

Some politicians might have taken the moment to be charming and ingratiating with the donors.

Not Mr. Trump. Over steak and baked potatoes, the former president tore through a bitter list of grievances.

He made it clear that people, including donors, needed to do more, appreciate him more and help him more.

He disparaged Vice President Kamala Harris as “retarded.” He complained about the number of Jews still backing Ms. Harris, saying they needed their heads examined for not supporting him despite everything he had done for the state of Israel.

At one point, Mr. Trump seemed to suggest that these donors had plenty to be grateful to him for. He boasted about how great he had been for their taxes, something that some privately noted wasn’t true for everyone in the room.