You write well. A few details it however takes:
From Paragraph 1:
Some people believe that they are deserved to earn it because of their high education, responsibility and skills while others are against of it
I prefer to place all or part of the main sentence at the end of the sentence. Like this:
While others are against..., some people believe.... . This focuses on the reader's attention on the complexity, rather than the simplicity, in this way address the essay's topic.
From Paragraph 2:
On the one hand, it is a true that most directors have higher education than its staffs. It is a face that when people's education level increases, rate of earning also rises, even directors are exemption. They are highly likely to have tertiary education from top universities. Furthermore, responsibility they shoulder is much heavy than others. Decision they made about business is matter of failure or success. They bear higher responsibility while competing in the stiff market. Therefore, their responsibility should be equivalent to their salary. Similarly, they are much skillful than others by acquiring leadership and communication skills that are vital for negotiations and deals.
I think you should narrow this point by giving one-two real-life story. Therefore, your readers are easy to follow what you are saying. But, overall you write well :)