On of the issues with pure ideas is that normally they don’t stand ground when execution starts. You can spend years on planning/designing but unless you have significant experience in development/design behind your back, you won’t be able to predict all possible issues with your idea and design to solve them. Meaning that even if you have money to finance whole enterprise and you can find talented people to work on it, your idea just might be not practical or actually fun when it all is assembled together. This is why it takes years to make a good game. Part of that time is making a content, which might be thrown away or rebuild as you have to change mechanics of the game when certain things just don’t work. The other part is watching how your game works and analyzing what is good / not good in its design or execution.
If you want to ever get into industry professionally, don’t start with a MMO, start with something like BomberMan, It might look simple but it’s not. With easier to use engine, like GameMaker you could get a taste for what it takes to make even a simple game fun. I’m not saying this because “making good games is hard” but because before designing an “economy for MMO” you have to learn what “designing” actually means.