Why did the People's Republic permit Hong Kong to thrive as a coastal enclave of Western-style capitalism and British colonialism for so long?

Hong Kong pumped billions of dollars of foreign exchange into China each year.

Explanation:

Hong Kong was governed by the United Kingdom for 1841 to 1941. Britain occuppated the territory during the First Opium War.

The Chinese-Hong Kong economy relationship has been interesting for China because they were complementary. China provided cheap labour and land while Hong Kong provided capital, management skills, marketing channels and infrastructure for external trading.