BEIJING -- With a modest salary, teaching is only one of the ordinary professions in China. However, things could be much different once teachers become online celebrities.

"The total revenue of my lessons this year is expected to exceed 3 million yuan ($455,858)," said Yan Yuanshen, who is known as "Slipper Bro" online. He provides online tutorials about China's graduate entrance exam.

Yan joined online education in 2014, when he was recovering from a car accident. He was then a postgraduate at university.

Unwilling to waste his time, he started sharing his experience about the exam online.

"Back then, people were not used to paying for Internet classes. I set my price at 1 yuan per class, and only a handful people signed up," Yan said.

Now he has a team of 40 teachers, and over 3,000 students have signed up for his training program. His most expensive program is worth 7,200 yuan per person, and nearly 300 students signed up this year.

Online education in China was worth 71.4 billion yuan in the third quarter this year, a more than 50 percent increase year on year, according to a report by Analysys, a data company.

Analysys predicts China's online education market will reach about 371.8 billion yuan in 2019.

"Thanks to the development of China's social media, people like me who have a certain kind of knowledge can contact an audience directly," Yan said.

For many Chinese living in big cities, fear of being left behind means they must pursue life-long learning to maintain a competitive edge.

"Nowadays, if you don't join an online reading club or pay for several online classes, it almost feels like you can't fit in the conversation," said Wan Yitian, 36, an Internet company employee.

She paid for four radio courses on Dedao App, one of the online teaching platforms. Last year, before changing jobs, she bought an online course to learn interview skills.

"Even though each class costs 199 yuan, it's worth it because the speakers are top scholars worldwide," she said.

Xue Zhaofeng, a renowned Peking University economics professor, set up an online course this year, which now has over 200,000 subscribers. With a subscription price of 199 yuan per person, his course is worth around 40 million yuan.

Xiang Hui, 43, is a specialist in car maintenance. He has taught offline courses for two years, and is now trying his lessons online.

"Although car maintenance and decoration skills need to be taught in person, some basic knowledge and exercises can be presented online, which saves commuting time and improves efficiency." Xiang said.

Despite the fact that more Chinese are willing to pay for knowledge, online courses face the risks of piracy. Yan found more than 300 copycats of his courses and materials online.

"The live streaming platform has taken action to protect our intellectual property rights, such as setting an expiry date for files and displaying viewer accounts on the video. This way, they can find out who is recording and reselling the videos," Yan said.

"Internet celebrities shouldn't be only people who have attractive appearances and provide recreational content," said Lu Jian of CCTalk, a live streaming education service.

"Teachers who give serious and valuable lessons can also be famous because customers need their knowledge," Lu said.