Why is black card rare?

Could you elaborate on why black cards are considered rare? I've heard whispers about their exclusivity but am not entirely clear on the specifics. Is it due to their limited issuance, stringent eligibility criteria, or perhaps a combination of both? Are black cards targeted specifically at high-net-worth individuals or is there a broader demographic in mind? I'm curious to understand the underlying factors that contribute to their rarity and perceived value in the financial world.