Yeah, it's wild that the bulk result of all the droplets in a system individually refracting the White light is essentially a uniform macroscopic refraction as though it had gone through some kind of super droplet.
Physics does some cool stuff sometimes!

Edit: Refraction not defraction

And there's typically three (triple rainbow), you just can't usually see all three.

Also: there is no pot of gold if there is no end of the rainbow. Let this sink in for a moment.

I have seen full circles and doubles. It's very beautiful. I also like that the background inside of a rainbow is often a different color than the background around it.

A cool thing happened a few weeks ago though. I saw the ends of the rainbow IN FRONT of the trees that were only 100m away. And when we drove past those trees it was in front of the next bunch of trees. Maybe it was just my eyes deceiving me, or maybe a rainbow only exists in the eyes of the beholder. Never saw that before.

This is interesting, but what I want to know is what shape they would be if water droplets were not round.

Like, if they were cuboid or pyramidal instead, would that change the shape of the rainbow?

I saw a full rainbow from a plane once. It was sick

Veritasium did about a year ago using a large glass sphere as a stand in for a raindrop to break down how we're seeing the various light refracted from its interior (or the millions of tiny spheres at one time actually). It's about 30 mins but there's a few points in the video where it hits you what you're seeing, and it's mind blowing. And none of it exists.

This is one of those weird things where our perception is dictated by our cultural biases.

If you were an intelligent alien coming to earth for the first time from a planet with no rainbows, you'd see one and think "Oh, what an interesting phenomenon! A circular refraction partially obscured by the ground!" - because of course there's no way that kind of optical phenomenon could be anything other than completely symmetrical. It's obvious if you think about it.

But as a human, right from being a child every single portrayal of a rainbow has them as an arc, and we were never given reason to think about it from an analytical perspective. So we never did.

Sun dog are kind of related aren't they?

You can see this for yourself if you have one of those hoses with the multiple nozzle settings. I forget which setting I had it on, but I blew my own mind seeing a rainbow ring messing around with one as a kid.

Look at the moon on a misty night, you'll see the full circle around it. Kinda tricky to have the right Moon and weather at the same time though.

arent they actually cones? and we just see a segment of that cone which appears as (half of) a ring?

Let me share that famous MIT lecture on rainbows again: https://youtu.be/iKUSWJWMSk4

My first encounter with this concept was playing Katamari Damacy. Once you've gotten big enough to roll up the rainbow, you get to see it's a full circle ⭕ 🌈

So where's the gold then?

This type of misinformation is exactly what I would expect from the leprechaun. "It's a circle, no need to search for the gold, move along". Nice try, I'm not buying it!