The military participates in airshows because it's good for morale, because it helps showcase capabilities, because it's good PR for military expenditures, and because it's good for recruitment. All of these effects are mostly because it's cool.

The other people flying in airshows are flying there because they love aviation and because it's cool (not so much the money :)

Maximally correct answer is "there are many reasons with complex interplay", and those reasons do include the fact it's cool! Being cool has interplay with morale, recruitment, and even their ham-fisted attempt at referencing geopolitics.

They'd be "more right" if they said in addition, but they just straight up said "No."

(Also where did you read a too many comments shtick?)