Patrick Seguin has lived in the same apartment in the Marais for 17 years. He opened his gallery in 1989. Thirty-seven years in the same business, buying the same way: slowly, and only what he actually believed in. Look at what's on his walls. A Warhol portrait from 1975 next to Jean Prouvé furniture from 1948. A Damien Hirst dot painting over a desk designed in 1948 by Charlotte Perriand and Pierre Jeanneret. A Mark Grotjahn from 2012 sharing a room with a Jean Royère sofa from the 1950s. Nothing in that apartment was bought because it was trending that week. It was bought because it was right — and it's still right decades later. That's the whole difference between a collector and a speculator. A speculator is chasing this quarter's winner. A collector is building something that still makes sense in 20 years, in 40 years, in a room their grandchildren will sit in. Quality doesn't need a flip. It needs time. Slow and steady isn't a consolation prize in this market — it's the only st...