Gold dragons are the ones most often killed by humans, who consider their scales to be extremely valuable. These golden scales grant them a high level of protection, similar to armor, and they use this to their advantage in battle.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

There really isn't much to say about Mad besides what his name already says;

He's stark, raving mad. He believes he's the animate, immortal god of statues, and that by default he's also the ruler of all dragon-kind. None of his invisible subjects listen to him, so he's always putting them to death. This scares his 'real' subjects into avoiding him completely, which has him convinced that they're evading the law. Unfortunately, none of his (imaginary) officials are capable of killing the 'real' subjects, despite being very good are terminating the fake ones.

Basically everyone just lets him live in his strive-ridden, 'high society' little world and tries to bother him as little as possible. No one really wants him to be chasing them around screaming for his imaginary official to arrest them.