Your computer becomes part of a DDoS botnet. You won't notice anything except slower internet, but your IP address is being used to attack governments and corporations.
There are community-made "Lite" versions of Windows 7 (e.g., , Tiny7 , Windows 7 Epsilon ). These remove bloatware, drivers for rare hardware, languages, and components like Windows Media Center and DVD Maker. Windows 7 Ultimate 64 Bit Highly Compressed 10mb
and technically impossible for a functional operating system Your computer becomes part of a DDoS botnet
To get Windows 7 down to 10MB, you would need a compression algorithm roughly 400 times more powerful than anything currently available to the public. If Microsoft had that kind of technology, they would be selling hard drives the size of postage stamps, not hiding it on a file-sharing site. : Microsoft officially ended support for Windows 7
: Microsoft officially ended support for Windows 7 on January 14, 2020. Using any version of it today leaves you vulnerable to unpatched security exploits. Microsoft Community Hub Authentic Windows 7 Specifications
: Some archives are filled with "junk" data or "dummy" files that compress well (like a billion zeros) to trick you. When extracted, they may expand to a large size but will not contain a bootable or working version of Windows.
Some uploaders fill an archive with a "null file" (a file consisting only of zeros) which compresses extremely well but contains no actual data. When extracted, it "inflates" to 3GB but cannot be used to install Windows.