Dropbox failed to do one thing: give people compelling reasons to put a growing amount of stuff there so they would keep paying for and upgrading their accounts.
Imagine these scenarios:
- A user dumps their photos into dropbox and automatically is granted a flickr quality site with all of their photos there and organized. They can add metadata in the site and dropbox just makes it "work". Now I want to keep putting photos up and need to keep upgrading and paying for my account. Dropbox could have taken on Flickr and any number of other photo sharing sites.
- A user dumps their music collection into dropbox and automatically get a private site they can use to listen to their collection. Now I have to keep paying for their service and upgrading to add new music. Dropbox could have taken on any number of music services.
- A user dumps the music they created into dropbox and automatically get a soundcloud like experience to share their music. Now I have to pay to keep sharing my creations and upgrading to add more. Dropbox is now taking on soundcloud, and any number of other music sharing services.
- A user dumps their videos into dropbox and automatically gets a youtube like channel they can use to share their works. Now Dropbox is taking on youtube...and video takes up a ton of storage.
Give a storefront now people can sell their music, art, videos and now their livelihoods are tied to paying for Dropbox to exist.
And on and on and on. Dropbox could have been hugely disruptive to any number of other sites and instead is a languishing file sharing site that's targeting enterprise customers (meanwhile enterprises are actively trying to block dropbox from their systems as it's an easy exfil route) -- and it's in a crowded space competing with companies who are making it necessary to have their file sharing services because they're tying all kinds of productivity applications to their storage (OneDrive, Gdrive, etc.) that enterprises are willing to approve even given possible exfil risks.