The moment you connect to the internet without Windows Updates (patched for over 200+ known exploits since 2023) and without Defender, you are an open target. Ransomware, EternalBlue exploits, and USB autorun viruses will have a field day.
Windows 8.1 Pro Super Lite Extreme: Maximizing Performance on Older Hardware Windows 8.1 Pro Super Lite Extreme 32 64-bit