Why does Saturn have rings?

 First of all, Saturn's rings are relatively young. In cosmological terms they're "new." They're only about 100 million years old.

And we have no idea how they formed. Saturn also has a ridiculous obliquity.

So, what happened? A clue is Titan, which has been rapidly migrating outward.

Saturn probably had another giant moon. Something happened to destabilize its orbit, it grazed the atmosphere and dragged material out (causing the rings) and then shot out...somewhere.

We'll probably never find it.

So, what caused that? Right now, we don't know. Something must have had an interesting gravitational effect on Saturn's system at some point.

It probably had stars in it.

Joking.

Mostly.