an armchair something

an armchair critic

One who speaks critically on topics one actually knows little to nothing about. My uncle is such an armchair critic about the classes I'm taking—the fact that he never went to college doesn't stop him from weighing in! Stop being an armchair critic and let me fix my car, since I actually know what I'm doing here!
See also: armchair, critic

an armchair traveler

One who speaks authoritatively about traveling despite not traveling often. Don't let him discourage you when he's just an armchair traveler who's never been out of the country!
See also: armchair, traveler
Farlex Dictionary of Idioms.

an armchair something

An armchair critic, fan, traveller, etc. is interested in a particular subject and may talk about it, but does not have any real experience of it. The last thing we need are words of wisdom from an armchair critic. This great book is ideal for both the travelling supporter and the armchair fan.
See also: armchair, something
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • drive (one) out of office
  • force (one) out of office
  • force out of office
  • give (one) (one's) head
  • give head
  • give somebody their head
  • give someone their head
  • cooking for one
  • 1FTR
  • as one door closes, another (one) opens