I worked for a company that handled a ton of personal data. Pretty much every person in Germany, including addresses, bank account details, etc.

On my first day there (fresh from university) I was given literally full read access to the entire database. And as I later found out by accident: they did not track any data exfiltration at all. I copied several gigabytes of data without anyone noticing.

Your data is only as secure as the least motivated data broker sees fit. And that’s not very fit.