Microsoft officially ended Extended Security Update (ESU) support for Windows 7 years ago. Running an unpatched, modified operating system on a machine connected to the modern internet leaves it completely exposed to remote execution exploits and malware campaigns. 3. Broken Digital Signatures and Updates

Installing an operating system modified by an anonymous third party requires absolute trust. Because the system files are unsealed and modified, a builder can easily inject deep-level malware, rootkits, or keyloggers that standard antivirus software cannot detect at startup.

FAQ about the end of support for Windows 7 | Microsoft Learn