an armchair critic, traveller, etc.

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 critic, traveller, etc.

a person who knows about a subject only from what they have heard or read and not from personal experience: He’s what you might call an ‘armchair traveller’, having never actually been outside Europe.
See also: armchair
Farlex Partner Idioms Dictionary
See also:
  • an armchair traveler
  • travel on (one's) own
  • do (one's) head in
  • do somebody's head in
  • do someone's head in
  • do your head in
  • (a)round the corner
  • around the corner
  • (a)round the bend
  • around the bend