Dazza Hui, founder of Travel to Success, a Shenzhen-based travel startup. [Photo provided to China Daily]

Mastering Cantonese offers both professional and social benefits, he says.

The company's niche position means less competition, affording more time to learn and grow.

And it appeals to a massive mainland customer base.

Lao's company has trained 20,000 registered students and professionals online and offline.

"The mainland is a very big market," he says.

"If you succeed in Shanghai, you can extend your business model in big cities like Beijing, Chengdu, Wuhan and Shenzhen."

Lao also aspires to use the language for cultural exchange.

"There are around 80 million Cantonese speakers worldwide. Language is the vehicle of local culture," he says. "We hope people on the mainland can better understand and communicate with Chinese in Hong Kong, Macao and overseas, using Cantonese."