Marketing Week Magazine in the UK analyses the market for secondhand goods - a market that, frankly, is dominated by books. The writer doesn’t truly understand what makes the used book market tick - there is no mention about how secondhand booksellers often supply products (books) that are not available in new condition. To understand the used book business, you need to grasp how books go out-of-print and they are going out of print very quickly these days because publishers are not keen to hold on to ‘backlist’ titles for too long.
If you wanted to go deeper into the secondhand book market, you’d analyse the food chain of booksellers - $1 booksellers with huge warehouses (all online), remainder sellers (online & wholesale), charity sellers (online and bricks and mortar), general used bookstores (who are mostly online too), specialist used bookshops (nearly always online as well), purely online sellers often operating from home and sometimes with a storage facility, and high-end rare and antiquarian sellers with upmarket shops (usually online too). And I’m just skimming over the surface here.