I don't understand what the big deal is with "cloud storage". If I want to store stuff I put it on an external drive.
If I want access to it on the road I bring a $20 thumb drive.
I backup everything to my Timecapsule AND backup the majority of my hard drive to Dropbox. That way I'm doubly protected. If my Timecapsule fails, is stolen or is destroyed, somehow, then I've still got most of my stuff on Dropbox.
The big thing which you don't seem to take into consideration, though, is the ability to access files you may not have planned to access. Or perhaps you are somewhere without your laptop and want to access a file. Or maybe you want to access a file on your phone.
The other thing Dropbox is great for is sharing files. Especially big ones. Collaborating with someone in a different place is SOOO much easier with Dropbox.
Basically, I don't think you really understand Dropbox.
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Dropbox, Groupon and all these other tech start ups are a bunch of complete idiots when it comes to business. Sure they invented a great product but there is nothing special or unique for Apple or Google to replicate. There are no barriers to entry in these products. They are better of selling them before the public realizes there is a failed business model and insufficient revenue and they cant get an IPO out.
It depends on what they're in it for. If they want to make a quick buck and get out, then they should sell as soon as they can. But believe it or not, not everyone thinks that way.
Pretty much any product or service can be replicated. Currently, Dropbox does what they do better than anyone and they have A LOT of people using their service. And they make a lot of money. Not sure why they need to sell out.
As for Groupon, I don't know much about how they make their money, but they seem to be doing pretty well.
Your comment about a failed business model is a head scratcher.