This whole debate over whether Twitter is worth $357trillionbillion is totally missing the point. Every company valuation is based upon branding, customers, profitability etc etc. Sure this one might be too high, but so are countless others even after years of results to clarify them.
If brand value is included then right now Twitter is hotter than most things; and that probably counts for one hell of a lot in an uncertain year.
Sure they haven't got the service profitable or the funding model right yet, but let's not forget Amazon and so many other Dotcom boom era launches took years to get close to profit... and now they are rolling in it. Pick a bank and tell me it's pre-crash value was realistic despite years of profits data to back it up.
All business valuations are educated guesses, we can argue about them til we fall asleep but we shouldn't put too much faith in any of them.