I suggest you that before investing, solve this problem.
Bots.
I can assure you, there is no way you can make an accurate human verification.
Problem here is that even if you slow down bots, you will slow down people and those with 10000 bots will be 10000 faster than any person.
Bots are a huge problem for your idea. Also the approach you are giving it. The oculus Rift is just a screen, has nothing to do with the system you want to create so stop focusing on it. (also, bots don't need screens)
I'll help you by debunking every single counter argument you have against bots. I have said it countless times in here so I get tired of it, but I'm a game dev and an entrepreneur. I know about this stuff and that's one of the reasons why I'm interested and I don't want you to lose a great deal of money before really evaluating the project.
I solved the problem pertaining to bots as I set here eating my Bees Brother's honey caramels: Let 'em run!
Still do everything possible to thwart the practice, but advertisers, the key source of revenue with this endeavor, would already know such may exist beforehand, as they already do with other enterprises incorporating ad-based funding, basing their purchases on that knowledge. I simply have such facts penned on the appropriate page directed toward potential advertisers on the site so that they won't be surprised later. Thus, the onus would be on me: To many bots, less ad revenue; Continue to thwart the practice, ad revenue remains constant or increases.
Again, thank you so kindly for your very valuable post.
~Bruno Kucinskas