One thing about facebook is they are extremely paranoid. They see a cool app or product and instead of thinking “oh if we had that we could do so many things”, they think “what if Oculus Rift becomes so popular that it could replace our platform…” The reason they are paranoid is because they know what many advertisers are finding out that their current platform does not offer a good ROI for advertisers. So while i dont doubt that there are people within facebook that want to see Oculus succeed i guarantee you if it doesnt take off facebook wont really care because they will see it as stopping a threat before it actually happened. Which can end up being the sad part of any big company buying a company with so much potential before it meets that potential.