Many entrepreneurs think they are building an empire or sparking a powder keg, when they are really trying to start a movement.
I think beginning with the wrong expectation will greatly increase your chances of failure. You need to be prepared for the movement lifestyle. It's struggling to get customers, fighting to get people to care, or even to get people to give your idea a ten-second glance.
My last company was a powder keg. My current one is a movement. The differences in day to day life are staggering.
Containment vs convincing. Short term success vs the long haul. Be prepared.
Empires are rare. They're rare because they take a lot of money, time, and conquest to build.
Canonical examples are Amazon and Zoho. They start with a city (books, network management). Then they take go out and conquer neighboring markets, with no end in sight.
Eventually empires have to start building all sorts of infrastructure. It gets complicated. You're probably not building an empire.
Powder kegs are also rare. They're rare because they're all about the perfect idea, which involves doing the right thing at the right time.
Canonical examples are Skype, I Can Has Cheezburger and now Chatroulette. Once released they immediately take off virally.
You spark that powder keg, and it explodes. Then it's all about containment. If you can keep it under control, you can make an awesome exit, e.g. Hotmail, but you can just as easily implode, e.g. Friendster.
In any case, you probably don't have a powder keg to spark.
Attempted movements are a dime a dozen. If you're in a startup, you're probably trying to start a movement.
Movements are all about getting followers. You simplify your core idea and construct a message. You court evangelists, one by one.
If you can do this, eventually your movement may grow on its own. If it's a mainstream enough idea, it could grow into a revolution. Canonical examples are Wikipedia and Twitter.
More likely though, if all goes well you'll end up with a good business with happy customers who tell other people in similar situations about your products.
When you have your idea, you like to think of it as a "game-changer," i.e. an empire or a powder keg. With high probability, it is neither. It's a movement. Of course, it could eventually turn into an empire (Google) or have its powder keg moment (Twitter). Bu it won't start out like that.