Security - Do I need a security solution for my MacBook considering the number of cyber threats?

What is malware on Mac? - Apple Support

Protect your Mac from malware - Apple Support

Ways to avoid malware and harmful apps on Mac - Apple Support

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

macOS contains powerful built-in security measures that will help you and your data to stay safe. They aren't foolproof, though. If you are infected with malware, visit https://malwarebytes.com and download the free application. There's no need to use the real-time protection feature or purchase the premium plan as long as you understand how to avoid malware.

AntiVirus, Disk Cleaner, Optimizers, Defrag, VPNs etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation. The Built-in Security of Big Sur is all that is required.

Besides - there are no known Viruses for macOS that self-replicate. As Learned Colleague @sea116 has already supplied very good links on protection from Malware / Adware