gold bug

Short definition from Wiktionary

Noun

1. 1
   A person with a particularly great enthusiasm for investing in gold (the metal).
2. 2
   A person who is opposed to fiat currency and supports a return to the gold standard.
3. 3
   A person who collects gold items.
4. 4
   A particularly great enthusiasm for gold — whether as an investment, a hoard, a collectible, or otherwise — portrayed figuratively as an arthropod that bites people and infects them, causing a mental illness.