The SQLite development team doesn’t run and operate a scaled set of sqlite instances serving 100,000 enterprise customers and 200 million consumer accounts. They don’t have to run a billing and account management system at scale and provide support for a sales and customer service organization. They aren’t responsible for managing an exabyte or so of other people’s data.

The core storage/synching engine of DropBox is pretty simple, sure. Running DropBox is a lot more than just building that piece of software.