Most people here have had good advice. The only thing I would add is that there's a difference between vision and delusion. Visionaries have a strong and clear focus, but are grounded enough to recognize the merits of their competition and work within the ecosystem that customers / users already enjoy. Delusionaries pour scorn on their competition (or even claim to be so revolutionary that they HAVE no competition), and try to create a walled garden or vendor lock-in with zero install base. Even Apple made iTunes for Windows.
My first job out of college was at a startup. The founders were reasonable people who were heavily influenced and invested in by a delusionary, who saw their company as a vehicle to realize his "vision" of how technology should work. As a result we never really managed to grow beyond a couple of million in revenue, and that mostly from what amounted to R&D outsourcing from large firms with technically naive execs. Said delusionary repeatedly vetoed our attempts to make our product more relevant to a wider range of customers since it would compromise his vision. I bailed out of frustration, and a year later one of our customers just outright bought the firm to acquire the founders. I heard the delusionary was very satisfied with his exit. :p
My first job out of college was at a startup. The founders were reasonable people who were heavily influenced and invested in by a delusionary, who saw their company as a vehicle to realize his "vision" of how technology should work. As a result we never really managed to grow beyond a couple of million in revenue, and that mostly from what amounted to R&D outsourcing from large firms with technically naive execs. Said delusionary repeatedly vetoed our attempts to make our product more relevant to a wider range of customers since it would compromise his vision. I bailed out of frustration, and a year later one of our customers just outright bought the firm to acquire the founders. I heard the delusionary was very satisfied with his exit. :p