While you cannot view private profiles without permission, there are legitimate tools and methods for monitoring online activity for specific, authorized purposes.
Most sites claiming to be "top" viewers are actually high-risk traps: Phishing Sites:
The website owners make money every time a user completes a survey or installs an app, while the user receives absolutely nothing. Hidden Risks of Using Private Profile Viewers
If your goal is to find information about a person who has a private Facebook profile, there are effective, ethical, and perfectly legal methods that do not involve scams or hacks.