I can’t speak to the complexity of hosting your own file storage service like this, first hand. However, I can say that one of the things you’re paying for with a service like Dropbox is for someone else to worry about handling hardware failure, maintaining availability and uptime, data redundancy, etc. These things are not simple to solve. IMO, anyone looking to self host their own cloud storage solution for critical data should carefully consider how to handle these issues before “going live.”