Seems like a very unlikely assumption. I know plenty of people who use the service, none are paying, where does the $40 come from?
Agree that the current accounts probably aren't worth $40/each - the valuation includes the technology, brand, and growth potential of course, not just the current userbase. But a lot of people will pay. Really, sharing big files used to be a major pain point online. Dropbox makes it ridiculously easy.
That's why.
All else being equal, wouldn't you pay more for a company with high growth potential than one with low growth potential?
How is it fair to say that? Is there any data that backs this up?
"Dropbox goes mobile"
They already have
"becomes a default backup/sync app on Android and iPhone"
Although this is possible, this seems like a far-fetched claim. Apple and Google already have their own backup/sync methods for their phones, it will be tough for Dropbox to become the default app.
"Dropbox becomes the place where I dump all my data, my own API, and lets services have access to different parts depending on settings, add $1B. Dropbox becomes mainstream and reaches 100M users, add $2B, ....."
Where are these numbers coming from?
2- All the numbers are arbitrary but imo not far fetched.
How many products have flopped because of the gap between what potential customers claimed to be willing to spend and what customers were actually willing to spend?
You're assuming that market cap is based on yearly earnings, which is simply wrong.