"Many books were too popular to borrow from the library," Wei says. "By reselling them after reading them I could read books at leisure very cheaply. The experience showed me that if we treat durable goods properly, everyone can use them without having to pay too much.

The dream of running a secondhand shop thus took root in Wei's mind, and in January last year she quit Alibaba, starting her online secondhand bookshop.

Her business started from groups in the social media app WeChat and she later set up a WeChat official account, with a mini-program to run the business. In March last year Wei had 5,000 books stored in her house in Wangjing, northeastern Beijing. After a year's growth, the warehouse she rented in a Beijing suburb had more than 20,000 books.

Continuing growth forced her to move twice as she sought more space to store all the secondhand books she received, once to Langfang in Hebei province and again to Tianjin. In July there were over 700,000 books in her 7,000-square-meter warehouse in Tianjin, Wei says.