Why is the work of the gas in a circular process not zero?

Because in this case, either the work of the gas is greater than the work done on the gas, or vice versa, the work done on the gas is more than the work of the gas.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.