"If it ain't broke, don't fix it!" That saying applies in many places, but NOT to computer hardware and software. It’s clear that many of today’s cyber attacks prey on vulnerabilities present in old software and hardware. This is especially true for operating systems such as Microsoft Windows.
It may not be “broke”, but it’s still old and very likely out-of-date. “Working” does not mean “secure”. Old software and hardware simply do not have the latest defenses like security patches and advances in firmware to keep you safe from new and ever-evolving threats. And depending on how old, some products are no longer supported or able to be upgraded at all.