The stablecoin sitting in your wallet after that watch sale could become inaccessible without warning. The good news is that, with the right expertise, it does not have to stay that way.

Marcus had done everything right. The Singapore-based watch collector had spent a decade assembling a carefully curated collection, and the crown jewel — a Patek Philippe Nautilus ref. 5711/1A in stainless steel, acquired at retail through a longstanding relationship with the boutique — had appreciated spectacularly. When a buyer approached him…