"Dropbox for VPN" makes no sense whatsoever, and even after reading the product description, I don't understand how it related to Dropbox at all.

If you read the about, it details the monicker. Basically, this infrastructure could allow for turnkey VPN networks and sharing of resources/files by way of "deperimetetization", wherein security is on a data level rather than a network level. Read the about; it's a copy-pasta from there.

Who has the appletv?

22:39:02.409865 IP 29.215.211.78.5353 > 224.0.0.251.5353: 0 [7q] PTR (QM)? _pdl-datastream._tcp.local. PTR (QM)? _appletv-pair._tcp.local. PTR (QM)? _appletv._tcp.local. PTR (QM)? _00000000-100f-a311-cde5-9ff59911484f._sub._appletv-v2._tcp.local. PTR (QM)? _00000000-100f-a311-cde5-9ff59911484f._sub._home-sharing._tcp.local. PTR (QM)? _touch-remote._tcp.local. PTR (QM)? _ica-networking2._tcp.local. (246)

Authentication is based upon an API call to http://api.zerotier.com/one/nc/randomhash. That returns a config file which includes the IP that you are given. Seems like it would be highly susceptible to an MITM attack.

Seems like an neat idea, creating an massive network on top of the internet, but how private is a VPN if it's free to signup & all clients are put onto the same /7 subnet? Isn't putting every client on one network less secure than how the internet normally functions?

So it's a massive broadcast network?

Where does Dropbox come into this?

Perhaps it's because I just woke up 20 minutes ago, but this makes zero sense to me. What am I missing?

Oh, so it's Hamachi, but public and private, and installing it on Mac doesn't require a hack. Ok.