And secondly, good hackers can be hired too; it is possible to replicate most things.

I think that valuable web entrepreneurs are, in general, good hackers and good businessmen. A lot of hackers think the business end isn't important and a lot of businessmen think the technology isn't important. They are wrong. You will probably have serious competition and you need to be prepared to compete.

This isn't a kind industry. A lot of teams get crushed. Your team ought to be able to compete on both the business and technical fronts.

edit: I noticed you are one of the founders of DropBox. I don't know a great deal about your product. But, as far as I can tell we agree. DropBox seems like a straightforward, simple, focused application.