... How much tax money do you think it would actually take? I think this is a false choice.

(Not that I think it's a good suggestion, but this is a bad reason not to do it).

I think creating a social network to compete with the likes of FB is going to be a hard problem, especially with the insane network effects of existing social media. I won't pretend that the server farms will somehow be prohibitively expensive, but the marketing might be.

Especially since it might not work. Right now everyone (unfortunately) is on existing networks and if you're a business that's what matters.