Is the imam's supplication for himself during congregational prayer considered a betrayal of the congregants, and is it permissible, or should he supplicate for them?

The supplication in which the Imam and the congregants share, and where it is disliked for the Imam to single himself out, is that upon which the congregants say "Ameen," such as the Qunut supplication. As for the instances where each worshiper supplicates for himself, such as the opening supplication (Du'a al-Istiftah), between the two prostrations, and after the Tashahhud, the Imam supplicates for himself, and the congregant supplicates for himself using the singular form. This is what is indicated by the authentic Hadiths agreed upon by scholars.