If you say that someone is on an ego trip, you are criticizing them for doing something for their own satisfaction and enjoyment, often to show that they think they are more important than other people.
[disapproval]
ego trip in British English
informal
noun
1.
something undertaken to boost or draw attention to a person's own image or appraisal of himself or herself
verbego-tripWord forms: -trips, -tripping or -tripped(intransitive)
2.
to act in this way
ego trip in American English
US
Slang
a trip, or experience, that gratifies or indulges the ego
Derived forms
ego-trip (ˈeˌgo-trip)
verb intransitiveWord forms: ˈego-ˌtripped or ˈego-ˌtripping
Examples of 'ego trip' in a sentence
ego trip
His ego trip ended abruptly when not a single hand was raised.
Secombe, Fred GOODBYE CURATE (2002)
Is there a single reason for anyone to own or drive a car like this, other than that they are on a total ego trip ?
Jonah Black THE BLACK BOOK: DIARY OF A TEENAGE STUD VOL. III: RUN, JONAH, RUN (2002)