Why diamond is the hardest metal?

Hardest metal is diamond because wayyy back when they decided to do test. They take car of diamond and ran it to a metal wall at the speed of light. The brick wall dissolved. Then they took a metal car and ran it into diamond wall at speed of light. Car dissolved. They then took speed of light car and drove it into wall made of metal at the speed of diamond. The earth shook but everything dissolved. Then they took diamond wall and drove it into a speed of metal wall and created muffin. This concluded that diamond is the hardest metal