As a high school student, I've had some ENTP teachers who all seemed very confident and proud, but turned out to be quite insecure.
The first was a history teacher who was 'full of himself'. He constantly talked about his material possessions (e.g. cars, branded goods), about how he knew lots of important people, how busy he was etc. He also cryptically avoided questions about his marital status. Either that or he would say he had a wife and kid in in some faraway land, but when we visited his home, we found no trace of any family (no clothes, no photos, nothing). And he would often try to groom 'favorite students' (but refuse to hand out a single A, trying to emphasize how difficult it was to succeed in his class). He would also call up students randomly and chat about his own life. He was definitely an ENTP though, very extroverted and thinking, couldn't organize his classes for nuts, and used fanciful and pretentious language only an N could muster.
The second was an English teacher. Definite ENTP - very E, very N, and very P. Couldn't organize a single lesson plan at all, spent the whole lesson talking about himself, and talked how he spent ages coming up with models and theories on how to write good essays and live life. Also loved to talk about his own life - e.g. his stint in the army (of course, he was in a secret vocation he couldn't talk about), his big motorbike, how objective and fair he was, how reasoned he could be, etc etc. Also remained very cryptic about his marital status. But on the other hand he can text some of his favorite students consistently everyday - talking about even the most random things, and almost confide in them. And he consistently sought reassurance about his teaching, his fairness, etc nearly every lesson.
Is this behavior typical of ENTPs - that they like to project a pumped-up image of themselves to hide the insecurities they may have?