Dropbox (employees and trusted third parties) will always have access to your files.
Before you downvote.
This is not necessarily a bad thing. They can deliver more features and better performance as a result. Reliability is key, and it's certainly easier to understand what users need, and to develop, implement and debug new features, when you've got access to the files users are storing.
But eventually, end-to-end encryption will take hold. It took decades for HTTPS to become the defacto standard, but it did. Email is moving that direction (Proton Mail, Tutanota). Text messaging is moving that direction (Signal, WhatsApp?). And there's a number of Dropbox competitors that are growing fast because of better privacy and E2E encryption (SpiderOak, Tresorit, Sync.com, pCloud). NextCloud (open source self-hosted Dropbox alternative) also just launched end-to-end encryption.
These companies have been slowly solving the problems that Drew claimed were impossible when Edward Snowden dropped the bomb. Meanwhile Dropbox has been pouring dollars into marketing and a Microsoft Office / OneNote / Google Docs competitor (Paper).
Drew's response to end-to-end encryption: https://techcrunch.com/2014/11/04/dropboxs-drew-houston-resp...
Dropbox risk factors (many unsolvable): https://www.sec.gov/Archives/edgar/data/1467623/000119312518...
I use Dropbox and feel the product is still the leader in terms of features, but I see the competition catching up, with better privacy (end-to-end encryption) built in.