Fledgling game designers often set goals more lofty than attainable. One frequently-seen aspiration is creating a new MMORPG, and why not? Designing a unique world from the ground up rich with content, lore, and socialization, not to mention the potential returns if the game becomes popular (or even a household name like World of Warcraft), is highly appealing. Unfortunately most people can't foresee the sheer scale of such a project. Here are the biggest hurdles to creating a successful MMO.
You need to hire a team. There's no way around it. While anyone with a little study and practice can create a simple mobile game, text-based adventure, or mod for an existing game, unless you and your gamer buddies happen to be experts in every possible creative field, you cannot build an MMO from scratch, let alone for free. You need a team of programmers, engine developers, 2D and 3D artists and animators, writers, scripters & storyboarders (if you have cinematics), voice actors, sound designers, Foley, and musicians. Not every professional is suited for every job, however (you might be a great voice actor, but can you do every character?) and not all are needed for every phase of development either, which brings me to my next point.
You need a schedule and a budget. Yes, making an MMO at this point is sounding less like fun and more like a job, but that's what it is! Your team won't be like a fire-and-forget DPS spell either. MMOs are in constant development with patches, expansions, and customer support. Be sure to hire team members you'll want to work with years from now.
But before you hire anyone, research the costs. Develop work pipeline flowcharts, Gantt charts, and detailed salaries and expense budgets. You won't need any musicians until later on, but you'll need developers immediately, and you certainly shouldn't hire voice actors if you don't have any scripts.
Research the market and make yourself known in it. Find out as much as you can about existing MMOs, the good, the bad, and the vaporware. Why is World of Warcraft so successful? Why was Everquest popular - and why isn't it anymore? Why did City of Heroes shut down? Why did the Titan Project get canceled before it could see the light of day? Track trends and make yourself a trend. Generate hype with aggressive marketing. Be sure to set aside a budget for advertising and PR.
Play as many MMOs as you can, but play them critically. Take notes of what you love and hate about your experiences. Write down common bugs. Take surveys. Lurk on forums and watch the discussions. Being a designer, like the game itself, will be a constant state of development and self-improvement.
Make games right now. If you've never made a game in your life, shelve the MMO for now and get cracking on something within reach already. Like I said above, anyone can get their feet wet with game design. A variety of free and cheap creative software and development kits will serve as the stepping stones for your future career. Make game mods, maps, and models. Program and create as much as you can and put it out there to receive critique - and make sure you're receptive to constructive criticism when you do.
Don't stop at just making games. Dabble in art and music to get a feel for it. Study film and cinematic techniques, even. Nothing you can learn now will ever be useless later. The more you know about different creative fields, the better you can understand the abilities and limitations of your team members in the future.
Creating a new MMORPG might seem like an insurmountable mountain right now. You might feel like you'll never see the MMO you've always wanted to make come to fruition if you're still stuck programming calculators and just trying to get a custom skin to work in The Sims (and it keeps crashing every time). But remember that everyone at Blizzard, Bioware, and Bethesda once stood exactly where you are. By understanding the scope of a task and committing yourself wholly to what it takes to accomplish it, someday you could have a million subscribers too.