A "bubble" isn't defined as the absence of any irrational valuations.
My go to example for this is Facebook's IPO. Their valuation was at the time at $50/user. Can they extract that much lifetime value out of every user they have? It seems rather high to me.
I don't believe there is an industry-wide bubble going on. But it seems to me that if you hit the right keywords (social, sharing, advertising), you will be valued at the top of the range, not the bottom. Moreover, I believe these particular valuations will get market corrected sooner or later.
But FB has real profits, so you may not wanna bet too much against them. They're also locking up users' Internet access in many markets, making it literally impossible to run a competitor (without negotiating the same ISP access).
Perhaps look at Splunk, which does great not only in losing money, but accelerating those losses. (Er, I mean, they "focus on top-line growth".) But hey, maybe they can cut their costs by over 2 (eliminating all R&D wouldn't be enough) but keep the revenue coming in. Then they could be profitable before other systems and hardware catch up. They're only 12 years old, so it's still very early in their long-term story.
There is no premium if you buy and hold, in fact that's the baseline situation from which the premium is calculated. And buy-and-hold works for arbitrary timescales, while even long term puts come only in certain flavors.
That starts to seem a lot like structurally built-in upward pressure on prices.