The reason why Zheng Jun is rich is mainly due to his musical talent and successful business operations. The following are some specific reasons:

1. Musical talent: Zheng Jun is a famous musician and songwriter, and his music works are deeply loved by the public. His music works have high sales volume in domestic and foreign markets, which provides a source of income for him.

2. Successful business operations: Zheng Jun not only achieved success in music creation, he also successfully combined his musical talent with business operations. He has been a guest and host at many music festivals, and has also been involved in some commercial activities, all of which have brought him substantial income.

3. Other investments: In addition to music creation and business activities, Zheng Jun may also be involved in other fields, such as stocks, real estate and other investments, which is one of the reasons for his increase in wealth.

In general, Zheng Jun is rich mainly due to his musical talent and successful business operations, as well as other investment areas that he may be involved in.