Luxury companies look like a rabbit caught in the headlights. The market for secondhand luxury goods is approaching a tipping point, but many brands can’t decide which way to jump.

Last year, the value of the luxury resale market hit 50 billion euros for the first time, based on estimates from Bain & Co., equivalent to $59 billion at current exchange rates. The resale business is growing faster than the primary market and is now the same size as all of the trade that luxury brands do through off-price outlets—their third-largest channel by sales.