No but seriously Newt oozes *in the book* a confidence that extends only to his thinking. He is a flustered little rabbit who probably wears like 12 jackets because he didn’t like the shirt he decided to wear.
This is very easy to believe in the movie without getting the prose the book gives. Don’t think about Charlie Day, who is comfortable with himself, but do think about his height and voice, and what a guy like Newt would have to deal with.
When he was younger, before puberty, he understood people were going to dismiss him. And his dad would reassure him that he was young and he would grow into his intelligence (ie people would take him more seriously when he was older), and he should just persevere. He shouldn’t change to fit in, and never sacrifice his ambitions to make other people like him.
But then puberty, and he gets taller and his voice changes, but he’s never as tall as the other kids in college (and later, his co-workers), and his voice never smooths out; it seems to be eternally cracking, and people snicker at him even when he’s talking about his second PhD.
He is insecure about everything at this point.Very few people truly respect him, and even at the end, some of those he thought did (especially Pentecost) flat out shut him down and aren’t interested in his ideas.
(Realistically, Pentecost does this because it truly is an extraordinarily dangerous proposition, and there’s so little information available, he and Herc Hansen critique his proposal on sound footing.)
Though I do like the idea that he’s comfortable in his own skin (he’s had 35 years to deal with it), but extremely uncomfortable around other people. The kaiju tattoos are an easy way to take the attention off himself and put them to something else, even though they’re a part of him. Or maybe it’s a way he can say “This is what I do, and I can tell you all about them if you’d just listen.” But he’s spent so much time defending himself, ever since he was a kid, and has spent far too long with Hermann, that he starts every conversation as a confrontation.
I think both Newt and Hermann, as presented in the movie, are insecure. They display it in vastly different ways, but yeah, both poor insecure babies.