The most valuable truths are the ones most people don't believe. They're like undervalued stocks. If you start with them, you'll have the whole field to yourself. So when you find an idea you know is good but most people disagree with, you should not merely ignore their objections, but push aggressively in that direction.
One could avoid privacy issues by not collecting any information outside of email and chats, I would imagine. You don't HAVE to collect lots of user information.
As for porn, why does a social network have to allow embedded images? If it's mainly a chat service, there's no risk. I suppose someone could use your network as transport for links to outside content, but that's pretty unlikely and it's a stretch to say the network is responsible at all. You could also disallow hyperlinking.
Of course, both of those fixes make the system pretty damn hard to monetize, which I think is the biggest issue.
Although you seem to condemn college students, it seems as though your concerns are all solved by moving the target audience to colleges, because college students are "adult" enough that we don't care about these issues for them for the most part (with respect to laws).
> Facebook, Instagram, Snapshat etc all struggle with this across their networks.
Pretty sure they all started by being built on similar user bases, and it's a tremendously appealing audience to start an app with.
