“I do not think there is an increase in fuel consumption with commercial airliners caused by an individual”
Sorry, but there is an increase in fuel consumption based on the weight of the aircraft. Some of you may recall episodes where the pilot came on the PA system and advised of a delay while they “took on more fuel” because the flight ended up carrying more passengers than forecast or more baggage.
Obviously, one or even five additional passengers on a wide-body aircraft won’t materially affect fuel consumption BUT unless they are in a zero gravity bubble within the fuselage, they will cause some very small increase in fuel consumption.