Wu Shichun is one of countless Chinese entrepreneurs who over the past four decades have prospered from access to American customers and money.

Today, as the American government threatens to take that away, the serial entrepreneur and venture capital investor is fundamentally rethinking how he does business.

One of his portfolio companies designs and makes fashion products in China, then sells to American consumers on Amazon.com. Another, a vape device maker, sells most of its products in the United States. The third, which makes metal materials for electronic manufacturers, exports 40 percent of its production there. All three would be hit by new American tariffs.

“From now on I’ll have to invest in companies that focus on the Chinese market,” said Mr. Wu, 42.

“I hope China and the U.S. can find a better way to coexist,” he said. “It doesn’t have to be mutually destructive.”