A couple of weeks ago, Maximillian Bittner, the C.E.O. of Paris-based resale platform Vestiaire Collective, stepped down from his post. Bittner, a German entrepreneur who likes to remind people that he sold an e-commerce business to Alibaba before investing his own money in Vestiaire, was confident that he could make the platform the first word in secondhand sales. After all, he had the advantage of being based in Europe, and Paris specifically, the center of the luxury industry. Vestiaire’s hybrid model—peer to peer, but with a vetting system for high-ticket purchases—could arguably be more profitable than a full consignment business, where the onus is on the store to procure, process, and distribute each individual product.