I used to undertake people like the person at the front of this queue just to make a point, even if I wasn’t in a hurry or keen to make progress. Dangerous? Generally not. Immature and impatient? Probably.
As I’ve got older, I’ve become a bit more typical British and tend to sit in the OP’s position stewing, though on occasion I still can’t help myself and just blast past on the inside.
The funny thing is, I’d say the majority of overtaking lane snails actually pull in to the middle or near side lane immediately after being undertaken, which suggests to me that most are simply being dozy and inattentive rather than entitled lane hogs.