>In particular anyone who does 'mileage runs' and emits huge amounts of CO2 just so they have the 'privilege' to sit in a slightly nicer chair in a dull airport lounge.

I doubt anyone is doing this? At best they're grinding out flights so they can get free first/business class seats later.

People do this to meet minimum requirements for mileage tiers, e.g. I know someone who was close to Diamond status on Delta and went to Miami and back without leaving the airport area just for the miles.