Besides, you said that 4000 yuan doesn't include food and accommodation, and the living standard in Shenzhen can only be considered barely, depending on which district you live in. If farmers build their own buildings, one room and one living room is generally 1500, and the living expenses are estimated to be within 2,500, leaving 1500.
I happen to be 4000, but after deducting social security tax and insurance, 3300, living at home and paying 1300 for living expenses, 2000 is still enough.