I feel like I heard this same thing before... just over a decade ago.
Here's the deal, economic value is all about returns on capital.
User value or some other sort of "value" may well fit with what you're arguing, but fundamentally, economic value is all about return on investment. That means how much is my investment growing? Growth, therefore, must be measured in real dollars. If it's not able to be converted into a liquid asset, it's not real, it's speculative. So, until such time as you can actually, demonstrably monetize the "value" you're asserting exists in a company like Pandora, is, in fact, speculation and nothing more.
Bubbles are driven by speculation en masse. Some people get rich in them (because they sell before the crash). Every time there's a bubble, people start talking about how the old rules don't apply. Thus far, every time, they've been wrong... and it's because to increase value, you need to be able to monetize the offering. If not, you're creating user value, but no economic value.
Over anything but short-runs, investors want returns on capital – because you can find them elsewhere... so if your capital is tied up in an investment that isn't actually producing monetizable products, it's not producing capital gains. Therefore, there's a clear opportunity cost associated with putting capital some place that it's not growing in any sort of real (i.e.: liquefiable way within some predictable timeline) – and if the investment stays like that for too long, investors will go elsewhere, for greener pastures.