In my teens I read countless fiction books - all of Stephen King's at that time, all of michael crichton, plus dozens of others. Problem is that was a very long time ago and none of it is clear in my mind. Hopefully the foundation of how it works is still with me.
Right now success is defined as monetary first, and second to entertain the reader for awhile. I'd love to write simply to please myself, but that may not pay the bills.
It's what you been reading since your teens that counts. It's never too late to start reading fiction, and to keep reading it until it soaks in.
Honestly, it's one heck of a lot easier to earn a good living writing nonfiction than it is writing fiction. Nonfiction not only sells extremely well, well enough to make a fair number of writers rich, there are far more nonfiction markets, and a far larger demand. But as with fiction, you have to write the kind of nonfiction that sells well.
I'm a firm believer in writing for money. Money is the primary reason I write. But I also believe in being realistic about it. Incredibly few fiction write even earn minimum wage, let alone earn a living, double let along get rich.
Even those who do manage to earn a living writing fiction usually put in a lot of years earning nothing before it happens.
Whether you write nonfiction or fiction, you have to have the talent, you have to have the knowledge, and you have to be ready to fail completely. Where writing is concerned, I don't believe in odds, and I don't believe in luck, but the fact remains that only a miniscule few have what it takes to even earn a scrape by living by writing fiction.
I'd also say that whether it's nonfiction or fiction, if you aren't writing for yourself, you probably aren't writing for readers, either. You're the one who has make it marketable, which means writing something YOU would want to read if someone else wrote it.
There isn't a thing in the world wrong with writing for money. There isn't a think in the world wrong with playing pro basketball for a living, either. Those who decide they' re going to write for money probably have about the same chance as those who want to play pro basketball for a living.
Still, I'm all for trying it. Just remember that you have to learn how to write fiction, just like a painter has to learn how to paint portraits. It's going to be hard at fist, and maybe always. You may have to write a dozen novels before you write one that's anywhere close to pro quality, if you ever do. Most do not.
The only answer is to read every bit of fiction you can get your hands on, sit down and write each and every day, and hope you have the talent and the dedication to see it through.