SHENZHEN, China—Life used to be good for Jerry Tang, who left his rural hometown in 2014 to become a real estate agent in Shenzhen, China’s tech megacity and one of the world’s hottest property markets. Just a few years ago, Tang could make up to 50,000 yuan ($7,800), in a good month, selling apartments. Last year, he was making around 15,000 yuan (about $2,348) a month, but this year that’s fallen to about 5,000 yuan ( about $783) and mostly comes from commissions on rentals. “It’s definitely much harder to sell this year,” he said. “Buyers are waiting to see what happens with the market, while developers are cash-strapped, they are taking time to pay commission to agents.” In Shenzhen, home to 17.6 million people and firms like gaming company Tencent Holdings Ltd. and telecommunications company Huawei Technologies, some smaller realtor offices have closed. Eight real estate agents Reuters spoke with …