HONG KONG — For years, no matter what was happening elsewhere, global companies bet billions upon billions of dollars that China’s consumers would keep spending money.

Now, just when the world economy could use their financial firepower, they are holding back, worried about the country’s slowing growth, a trade war with the United States and rising amounts of personal debt.

Zhao Zheng, 26, is among the cost-conscious consumers.

On Thursday, Mr. Zhao, a real estate agent, was browsing smartphones made by Xiaomi, a Chinese rival to Apple that prices its handsets at a fraction of what the American tech giant charges for iPhones. He said the success in China of Xiaomi and Miniso, a chain of low-cost variety stores, suggested that Chinese consumers were looking to get more for their money.

“The economy,” Mr. Zhao said, “is definitely very bad.”

A significant pullback could have a big impact on a world looking for engines of growth, on companies that counted on China’s continuing expansion and on global investors who have long viewed Chinese consumers as a steady source of profits.