The wording of the headline is odd, but the article discusses flying for leisure - going on vacation, etc. - not flying as a recreational activity unto itself. The article doesn’t really discuss whether flying is fun or not, as its primary focus is on the environmental impact of passenger jets. The author has cut down the amount they fly, and defers to taking rail instead whenever possible.

The use of the word “fun“ in the title is likely meant to contrast between flying for work purposes.