I plan to buy Twitter stock as a hedge against actual intelligence in the investing community. Seriously, the true valuation on a non-profitable company with no reasonable way to make a profit is $0b.
That is until the ad money starts generating that much neede revenue. For now, valuations can be done on multiples of assets, sales or market value of similar companoes
Twitter ads are never going to produce a substantial profit. Google and Facebook have the ability to mine a ton of data that will eventually allow them to provide perfectly targeted ads that 1) don't annoy you, and 2) produce a ton of profit. Twitter knows when you last went to the bathroom. I'd expect the ads to increase, become obtrusive, and people leave in masses if that is their monetization end-game.