"The investment, the policy and the timing mean it has never been better for the mobile Internet sector in China," Li, vice-president of Yicuntongda, said. "A comfortable job at a big company does not satisfy those who have dreams and ambitions."

To illustrate this innovative tide sweeping the industry, about 15,000 Tencent employees have quit their jobs since the company was founded in 1998, Nan Ji Quan, the official company alumniorganization, highlighted. The total work force of Tencent is now between 25,000 to 30,000 employees.

"In the past few years, about 10 percent of the staff have left Tencent annually for other opportunities," Shen Ning, the Beijing head of Nan Ji Quan, which means Antarctic Circle, a reference to Tencent's penguin mascot, said. "An estimated 3 percent to 5 percent moved on to set up their own businesses or join startups."

But those sort of turnover figures are normal for a major company such as Tencent and will not affect the firm's future prospects.

"For those who are already working for one of the A-list Internet companies in China, the chance to move to a similar organization can be limited," Shen said. "But joining a startup firm is a new challenge. It is the chance to build something, which could be a potential game changer."

Still, not every employee at the Big Three is entrepreneurial material. Sidney Wen, a venture capitalist at Keytone Ventures, a China-focused fund, compared the hiring process to the dating game or finding the right partner.

"Naturally, they look attractive to investors," he said. "But despite the shining halos that hover above their heads, it is important to know what are their strengths and what they can bring to the table."

Keytone Ventures has invested in projects launched by alumni from Tencent and Alibaba. "But you still need to be rational about this group, even very good employees at big firms can be very bad entrepreneurs," Wen said.

Naturally, the strength of the Big Three is their user base, which is in the hundreds of millions. Small companies can attract less than 1 million users. "The difference in the size of these bases illustrate the huge gaps in understanding potential users. It is like the different views you see from a big mountain and a small hill," Peng Wangcheng, a Tencent employee turned entrepreneur, said.

He admitted that working at big companies is like standing on the shoulders of giants. "You only need to focus on what you do best," Peng, who joined DaDa Bus in March, an app dedicated to improving the commute to work on buses for white-collar workers, said. "But working at a startup is completely different. You need to focus on the bigger picture."

Although the risk of failure is high, Peng and his team of 20-somethings are up for the challenge. "To lose a great business opportunity during this growth period of the mobile Internet would be unbearable," he said.

Ma Si and Cai Xiao contributed to this story.