Why do we love stories so?

It always is to live other lives vicariously.
- Seriously.
  I can hear directly from the horse's mouth from someone who went through World War 2, fought in a trench and saw all the tanks, saw their friends die, had all these crazy experiences.
  I watched Dunkirk and I didn't like it because it was all a bunch of crap. Roald Dahl already told me how it was (not in France, in Greece, but sort of the same situation) and it just wasn't like that. He watched German fighters buzzing around and picking off ships in the bay, from up on the hill, he went up in the air and flew around with bullets whizzing all around him, and then he showed them to me. Even if someone's not an expert writer, if they were there, then they can tell you. Someone who just works in an office in Hollywood probably can't tell you shit.
  I can hear from someone who worked in a hospital ER, someone who survived a concentration camp, someone who lived in the boonies in Africa and got out and yelled at the giraffes and had scares with lions and poisonous snakes. Redmond O'Hanlon took me up the river in Borneo and we ate cooked worms together and the guides had a little celebration because they thought we'd never make it through the jungle because we're old and fat and white. I saw Gene Kranz walk outside the building and cry, because in one of the simulations he fucked up and killed the whole crew, and he couldn't handle thinking of it if it had been real. I was there the night that Elie Wiesel's father died in the camps.
  JRR Tolkien learned the secrets of life and death in the worst places in the world and he told them to me, the best he could put them together. Richard Adams too, and Harlan Ellison.
  Is it the same as being there? Not even close. Is it better than just going to the store and talking with my coworkers? Fuck yeah it is.

For whatever reason, our brains developed the inclination/compulsion to imagine scenarios which greatly improved our odds of survival in the wild. In a biological sense, I figure stories and the like trigger that reward center in a way. Why people like different stories would come down to brain chemistry.
- It has always been so. When your sitting by the fire and the mind wanders, the days hunt comes crawling through your mind so you speak the story of the brave beast that nearly had you fooled and how thankful you are to have such a bounty. A remembrance of the sacrifice. The life taken so your children can flourish. A lesson for the young. Like a bee dancing in the hive, a tale with purpose.
  It is our nature.

I believe our consciousnesses are narrative based. That's the magic. Every thought idea etc is a narrative.
Stack up a bunch of narratives, hormones, and a grab bag of whatever instincts a few hundred million years of evolution has trickled down, shove it all in a meat sack, and viola! Behold a human!

We have to.

Stories are medicine.
It's one healthy way for our brains to process situations, dreams, aspirations, fears and experience. And it works.

I believe it is just a symptom of having imagination, being social animals, and developing speech/language. We see patterns and analyze things intently, have a desire to inform others of our discoveries and thoughts, and have multitudes of ways of doing so; stories are just a product of that. They teach, they inspire, they make us feel good and they also take some of the load of doing "background simulations" in our minds by having another mind do it.

Stories carry ideas and ideas is what moves humans.
We are not satisfied with what is. As a species, our survival at some point depended on changing the world around us, not just enduring it.
Be it an uplifting story or a cautionary tale, the ideas inside carry meaning and individuals will build a part of their worldview around it.

Terry Pratchett proposed in The Science of Discworld (which is actually more about the real world than Discworld) to rename the human species from Homo Sapiens Sapiens to Pan Narensis, the story telling ape. Since communication and telling stories is mostly what's separating us from other apes.

They create and release tension, like a joke, which creates a pleasure burst greater than the discomfort of the tension.
Starting from basically birth, we learn. Learning is the process of creating models in our heads of corresponding causes and effects. This is what makes intelligence powerful. You can know, to a point, what is going to happen before it does. However, the causes in reality are complex and not always perceivable. When this happens, we experience emotional discomfort, the fear of the unpredictable. In stories, there is nothing but the story, so everything is built to create and then satisfy that sense of tension. This is the pleasure of learning.

So, I'm gonna tell you a story.
The country I was born in is a dictatorship. Life was shit. I left when I was a kid to a country with more freedoms. I grew up to learn what freedom meant. Then when I was 18, I decided to return to the place of my birth and lead a rebellion against the dictator that tyrannized my country and the tyrant was defeated and everyone lived happily ever after.
Just kidding (the italicized part is false), I just lived a boring life in the new country as a background character, and my parents are abusive, I had zero friends, and my new country is also becoming a dictatorship, and everything is falling apart, and I have zero qualities of what a movie hero has, I never felt brave enough to attend a protest because I fear torture as a non-native-born citizen, and I have no power to stop anything and I'm gonna die in a gulag, the end.
I mean... see... the second story is so boring, that why we wanna imagine a world where the first scenario happens. Otherwise the world is just too dark without any beacon of hope.

Anecdotal, but I actually stopped liking fictional stories at some point, because I realized there's such an abundance of cool and real stories I could be learning about, that it's just like "Why are you telling me of a phoenix/dragon/Lavados when there's black hawks setting fire to Australia?".
I guess, it also ties in, though, that I don't do escapism in general either, so I don't either get lost in real stories, nor drugs.
I had a rough point in my life where escapism was crucial – I certainly don't judge anyone wanting to step outside of this world for some time – but yeah, that changed my fundamental world view, so that I prefer to stay in the real world now.

Stories are the medium through which we understand the world.
- I thought that was models?
  
  Think about how you consider your life: do you think of it as a model? Or a story?
  
  Nah, modeling is something that has to be learned. Making up stories is much more natural and our usual first response. Even really basic things have, at times, been attributed to the lives and mechanations of spirits.

They’re fun lol. Shit gets boring sometimes.