I would argue, and often have, that while money, technology and innovation (I'll come back to this) are considered more glamorous and therefore more important, communication is the single most critical factor in the success of any endeavor.
Communication is what transforms an idea into a vision, defines how it's different, explains why it will work, and engages people in helping make it a reality. Communication is what keeps your vision alive, whether you are in the room explaining it to someone, or they are thinking about it in places far from where you've ever been or will ever go.