You’re getting downvoted, but you’re right. Accessibility and security of data are two parts of the triad that require the most balancing. By its very nature, security is reduced as you increase accessibility, and vice versa.

The key word here is guarantee though. It is possible to make it extremely difficult to get the data without proper access—just not impossible. Some of the methods used today are pretty slick, but I’ve already forgotten most of what was covered in my network security course. I mostly just remember thinking “this isn’t for me” and “please make this stop”.