The main reason is speculative plot armor. Also we never saw a body

I don’t think you need to see a body when it comes to having over a hundred feet of stone collapse on you.

^not true.

And also I don't think she meant to kill herself, I think she was just really angry at herself for all the harm she caused

When have you ever seen anybody live through that?

Dude she's one of the most powerful characters in the MCU, if not the most powerful

Invulnerability is not one of her powers.

Then why the Hell didn't Pietro Maximoff survive his death from bullets in Age of Ultron!? I WANT HIM BACK!!! DAMN IT!

We saw the body...

There are many ways she could have survived. We didn't see a body, which was prob intentional. It's meant to be left to the audience's interpretation. She could have created a force field, or teleported away last second. Who knows?

Or maybe she died, and that's that. But I doubt it.

In all superhero media, the rule is: no body, no death. Even with a body, there is a possibility of no death unless you are Uncle Ben or Bruce Wayne's parents.

We never saw Wanda's corpse under the rubble. She may have teleported or had a force field around her body when the castle collapsed. There's a number of ways the Scarlet Witch could have used chaos magic to survive, or some other force could have saved her. Plus, it doesn't seem like Elizabeth Olsen is done with the MCU yet, especially since the Agatha Harkness series was renamed to Agatha: Coven of Chaos.