yeah I'll second Qre:us and sim, what they say rings true for me, as does your friend's thing about insecurity, etc.
the idea that ENTP's don't struggle with their extraversion is ludicrous in light of the number of threads on this board devoted to ENTP's who've taken a long time to realise that they were not INTP's, because as children/teens and even young adults, they've been very insecure and socially anxious, and struggled to socialise successfully despite feeling driven to do so.
I know an ESTP and to begin with we didn't get along very well. I thought he was a dumb meat head and he thought I was an airy fairy wuss, and a smart alec, and that I thought I was better than him - well, I guess in all honesty the last one was true in a way in that I thought I was smarter than him, though I never thought being smarter makes you a better person. I used to find him quite frightening because he seemed to me like a loose canon - so willing to become confrontational and (apparently) aggressive in order to "win" a discussion (i.e. intimidate everyone into not voicing their dissent).
HOWEVER, time passed and we were thrown together, had to work together not by our own choice, and after some uneasy times we started to get to know each other. I realized that his aggression wasn't actually genuine aggression - he was just testing if I believed in what I said enough to stand by it, and I learned that all I had to do was calmly stand my ground and he'd respect that and usually back down. But also that it worked the same way in reverse - if I thought something he said was screwy, I just had to come right out and say it without flinching, and if he felt sure he was right he'd usually stand by it calmly and then I had to back down. I learned that he very rarely actually stands by things when challenged UNLESS he's completely certain he's right, so if he's not backing down, I probably should unless I'm equally sure he's wrong, which seldom happens.
He learned that I'm not a smart alec - I'm just trying to treat everyone as equals, so if I'm using "long words" then it's not because I want to show off or make people feel inferior, as he thought at first, it's just the opposite in fact - to not use long words (which are my natural vocab) would feel to me like I was condescending to the other person and saying they were too stupid to understand if I talk my usual way, so I have to dumb down for them. And if I point out inconsistencies and stuff, it's because I think their idea/plan/whatever is actually pretty good, and can work, as long as these minor details are given due attention.
I learned that he's a lot smarter than I thought, he just applies his intelligence in other ways. But all in all I think the biggest revelation to me was about the intimidation/aggression thing. That was the biggest stumbling block for me that made it hard for me to respect him or really see him as someone I could feasibly have a real conversation with - I felt like there was no point, because as soon as I hit on something he didn't understand or didn't like, he'd just start getting all confrontational, and I don't have the inclination or energy to battle through that, so what's the point?
But once I learned that it wasn't actually true aggression and that he didn't actually intend to fight over those things, that he was just pushing me as it were, to see if I'd fall, I realized it was his way of testing whether I was worth listening to, that made a world of difference. It changed the way I perceived him and made me totally lose that fear and unease that I felt around him that came from what I believed was a constant threat/possibility of violence. That made me feel able to open up and just be natural around him. And that I think made him feel more able to do the same with me.
There, I dunno how representative that is of general ENTP/ESTP relations, but it's my experience, so maybe something there will ring a bell.