Fair point, but there are other players in the regime who do have future political careers to worry about. Vance and Rubio can still be burned by a humiliating deal; Hegseth and the "Deus Volt" wing might also be inclined to push back on a deal which stops short of Armageddon and the Rapture.
None of these people have careers other than fascism though. Their ability to maintain power depends entirely on their ability to successfully complete a fascist takeover of the United States which means that they don't have to care about popular opinions of their disastrous wars.