butterfly is interesting because it's faster than breaststroke (mentioned) but slower than freestyle. it also consumes far more energy than any other stroke.
to that end, i'm not sure why it exists, except that it's truly a unique style.
* i also still hold my high school's butterfly record, 20 years on.
The modern Olympics is at least as much for entertainment as it is for measuring human ability, and the butterfly is simply an awe-inspiring technique. The line of swimmers repeatedly shooting out of the water like flying fish is mesmerizing. Who cares if they're not going as fast as freestyle?
Funny I hated swimming but I was good at it, also did butterfly and freestyle. Everyone had to do the 500 at least once, that was brutal.
I think the objective is to show how strong you are. If you wanna go fast, use freestyle, if you want to conserve energy, use breaststroke or backstroke. I don't see a reason to use the butterfly outside of a butterfly competition.
> to that end, i'm not sure why it exists, except that it's truly a unique style.
Many people swim as a form of exercise. Fly is exercising different muscles and allows me to get my heart rate up higher than freestyle
Fly is useful to train for other strokes
Perhaps more importantly, I think that having a different stroke to do makes swimming more interesting. Whether doing sets as part of a swim team or on your own, it's more interesting when you can vary things. The more swimming is interesting, the easier it is to enjoy and keep doing it