Hello. I would like to draw your attention to the fact that Dropbox has been around for almost 13 years and has over 600 million users. During this time, there was no shortage of problems. Some of them were hacked, but many of the Dropbox reviews here
https://dropbox.pissedconsumer.com/customer-service.html show that the problem with Dropbox lies in the way this cloud service handles user data. The Dropbox security whitepaper describes how Dropbox Business protects its users' devices, but there is no equivalent for the security of personal files.