What is a person's ace?

Could you please clarify what you mean by 'a person's ace'? In the context of cryptocurrency and finance, it's not a commonly used term. Are you referring to a person's unique advantage, skill, or asset in the world of finance or cryptocurrency? Or perhaps you're asking about a specific tool, technology, or strategy that someone might employ to gain an edge in the market? Without more context, it's difficult to give a precise answer, but I'd be happy to explore the question further if you could elaborate on your meaning.