[new12345]

I don't understand inspite of having working p2p protocol why we don't yet have an good p2p alternative to dropbox that just works without any setup hassles. Closest working thing I know of is BitSync but that too requires an mediator server.

[yholio]

Because Dropbox is a file storage service, not a file distribution system. The typical use case is that an uploaded large file will be downloaded a single time by someone else, at different times when computers are online.

This requires an intermediary system with very high availability and performance, which in P2P can only be implemented by duplicating data on a dozen or so systems.

Since files must be private and there is no commonality like in BitTorrent, it follows that running a P2P Dropbox would consume 5-10 times the storage and bandwidth of it's centralized counterpart for the same useful service.

[amitport]

IMO. The p2p business model is problematic in this case.

1 People need to incentives to join a p2p network and certainly to contribute storage+bandwidth

1* Reliably and privacy issues makes this a bigger problem (though p2p may also be the solution, it's not easily achievable)

2 This can't easily happen without investment. Marketing + setup without "hassles" is not cheap

2* Given investment, what are the assets of the investors?

[e12e]

Ipfs doesn't take much setup, but it's global sharing - so you'll have to bring your own access control (eg: encrypt the files, and use à key distribution/sharing scheme of some sort).

[jonathanstrange]

I'm out of the loop for a few years now, but isn't NAT hole punching still one of the biggest problems? AFAIK, there is still no reliable solution that works without an accessible 3rd party server.