I'd like to add some more corrections to Hellomotor's version. I'm not quite sure if I'm right either so of course we dont' have discussions for nothing. :)
In today’s rapidly developing society, people are likely to stick their adult lives to certain jobs. That explains quite well why satisfaction with jobs reflects people's fulfilment of lives. Therefore, it is necessary to understand what job satisfaction is and how realistic it is for all workers.
It is my conviction that attitude of an individual towards his job is heavily dependent on numerous factors, including the two most influential being salary and happiness with the job itself. It appears that the former element directly affects the satisfaction of work. Apparently, earnings from work contribute to income of a whole family and that is vital. For that reason, an individual will be pleased when how much he earns is sufficient for every member of his family. The latter factor also plays a significant role to some extent. The fact is that many people are working for not only their families but also the passion for their works and that they are willing to devote their lives to chosen careers. The so-called noun "workaholic" refers to who are addicted to work, which means they are fully satisfied with their jobs literally.
It is believed that many people are dissatisfied with their earnings and their jobs so it would seem unrealistic to expect job satisfaction for all workers. In reality, money is certainly not the only element that an individual would anticipate. There are many other external principles affecting their satisfaction at work such as subordinate-superior relationship or promotion chances. For example, people will react in a positive manner to a helpful boss who shares experience with them or gives them useful recommendation. Accordingly, a person will possibly get a more interesting job or a boring one compared to what they have expected.
From all the things concerned above, I strongly hold the opinion that people nowadays are working in their pursuit of income rather than personal demand.
in blue: parallel structures needed in the previous versionHowever those corrections above are only about grammars and structures. I'm not so clear about some of your ideas. I agree with Hellomotor's on this matter.
Additionally, from what I've learnt, in academic writings you should not use so many "wh" clauses being subjects and objects (chủ ngữ và tân ngữ) for example "For that reason, an individual will be pleased when
how much he earns is sufficient for every member of his family." You'd better convert some of them into noun phrases.
Btw, I'm not familiar with Ielts writing tasks. I find it a bit weird that an essay has more than one issues to write about. :-s