When can an artist become a businessman?
A very long time ago I remember watching an episode of The White Shadow, a show about an urban high school basketball team coached by an ex-pro. The episode sticks out for having the Harlem Globtrotters... but I never forgot the point the episode made. Here's a Youtube clip from the episode, but leave it to someone to only show the basketball and not the final scene that made the point!
The kids meet the Globetrotters working at a car wash and make fun of them (not knowing who they are) for not being "basketball stars" like themselves, but rather, "manual labor." They're challenged to a game, and the game is fun to watch (those guys make basketball look so effortless). What the clip misses is the last sequence when the kids shut out the lights and run away from the obviously better players. When they're coaxed to return to the court, the Globetrotters are in uniform. No wonder they were being beaten!
And that brought us to the point of the episode (and the part that's salient here). The coach had the Globetrotters introduce themselves. They did, each giving their name...
... and their college degree1...
Cool story, grandpa, what's the point?
I'll be honest with you, unless you were born with an unholy talent for worldbuilding, you can't just quit your day job. Here on this Stack it's all about creativity and having fun.
But in the real world, it's about results, deadlines, and the bottom line.
Artists have always needed patrons
The simple reality is that you can't easily peddle worldbuilding on the side of the street any more than you can art. Oh, you can busk for donations, sell at fairs, yada yada yada, but if you want a profession, then you need to be (must be!) as much the businessman as you are the artist.
Why do people buy art?
And that's "art" in any form: music, writing, movies, theater, paintings, sculpture... worlds.... There's a lot of it out there. There always has been. The average person buys a little of it. But no one can make a living on onsey-twosey sales. That means you need to build one world that's whomping valuable, or you need to build a lot of worlds and make a little off each one.
Practical business... it's a harsh task master. And that brings us to those college degrees the Globetrotters have. We can give you pointers, but in the end, what you're doing is developing a business, not worldbuilding. In my experience, if you don't think of it like that, you'll be a starving artist.
What kinds of degrees are useful?
- Creative writing
- Engineering (problem solving!)
- Business management
- Data Monetization
I know that what you want to do is spend your time building worlds — but you'll need to spend as much or more time building your business. If you hang your painting up for the world to see and expect it to sell, it'll take eons to sell (the world is full of paintings with little "$100-" stickers on them. They're in restaurants, truck stops....) You need to find channels willing to distribute your art and ways to present it enticingly. That's where all those degrees (classes...) come in. It's not that you need all the degrees, only that you need at least one degree to teach you how to learn so you can learn what you need to know to solve this problem (it's just another worldbuilding problem, after all).
I like @TerranAmbassador's answer, I just wish he'd/she'd fleshed it out
The classic solution is to be hired by somebody to help build their world. Video game designers are at the top of the list, but so, too, are authors and movie production companies (and the subsidiary companies they depend on). This is the classic 9-5 paid job where someone brings you and idea and you're expected to flesh out that idea. It's what a graphic illustrator is compared to full-on-canvas painter.2
But we live in a world that has amazing grass-roots solutions. As TerranAmbassador suggests, you can make money indirectly by advertising to people who visit your website, youtube channel, blog, etc. to enjoy your creativity. Unfortunately, this usually requires building a considerable world for people to enjoy, and presenting that world in a way they will enjoy, before they'll show up in numbers great enough for you to quit your day job. In that regard, it's not a whole lot different from writing a book. You're going to make (for a book) \$0.35-\$1.25 per copy depending on the size and nature of the book and your contract with a publisher or distributor. To quit your day job you need to sell 35,000 - 60,000 copies.
Now we're back to those degrees. Because unless you're already rich, you need to know...
- Social Networking
I don't want to get you down about this. I've met people who looked at this mountain, took a deep breath, and pushed forward hard. And made millions. Why can't I do it? Because my interests are too diverse to allow that kind of focus — said another way, I'm unwilling to pay the price.
If you're looking for an easy solution, it's unlikely anyone can help you.
But if you're willing to pay the price, I think an entire new arm of questions for this Stack can help you. There aren't just a lot of engineers here, there are marketers, authors, publishers, businessfolk... I think there's a lot of talent on this Stack that can help build and develop a career in Worldbuilding.
Which leaves as a final question, do you have what it takes?
OK, one last thought...
From my experience as an engineer I can tell you that people do NOT pay for creativity. They pay for solutions. Creative solutions get the best pay. But the "creative" part is a distinct second place. From that perspective, you could monetize fully fleshed out chunks of a world.
For example, a creature. Full art rendering, complete description. Pros, cons, attack values, defensive abilities, contribution to the ecology, the works. And then you start pitching the creature to the film and game industries. The role-playing industry, etc.
Or you create mini-worlds (aka "game modules") for role-playing games and license them through the various RPG companies. That's still a pretty big industry, and that's likely the easiest entry into the world of professional worldbuilding.
Just remember, people generally don't pay for cool ideas. They pay for working solutions. A cool working solution gets a premium.
NOTE: I couldn't help it, when I saw this online, I had to include it in my answer because I remembered @Nick012000's comment. Ladies and gentlemen, I give you... Crown of the Oathbreaker from ELDERBRAIN. A 916-page "module" for Dungeons and Dragons 5e. I've never played a 5e game... I cut my teeth on "version one" — you know, the one in the box with the crappy dice that chipped each time you used them. Oh, I played the books for years (and I'm a proud owner of a copy of the original Chainmail!). But the idea of owning a single "module" that would have required my entire childhood to play... that tickles my fancy. Yup, it's AD&D. You'd be hard pressed to make money making modules for Gammaworld, Twilight 2000, or Paranoia, But the world would be a better place if you did!
1 Not all Globetrotters have college degrees, but most do. They had to. They're successful because of enormous talent, hard work, and better-than-average thinking. College degrees teach you how to do that third item and help tremendously with the second.
2 And you should expect the envy/contempt behavior. As in the oil painters have enormous contempt for graphic illustrators while envying their cash flow, and the graphic illustrators have enormous contempt for the oil painter's failure to monetize their talent but all the envy in the world that they're painting on canvas.... It's a stereotype, but I've seen the perhaps unconscious behavior all too often.