How a person with diverse background can select a specific career for his better future?

It depends on the person. The advantage though remains with the person having diverse background for me. Let us seggregate diverse background into the person's education and person's experience. People who have diverse education have studied different subjects and thus can choose from them those disciplines which they find interesting to learn. 

Now, diversity in experience is also effective in today's marketplace. Have a look around you and most of them would say there are no jobs. There are jobs but for those who can offer more MONEY to the organisation. Yes, MONEY is blood for most of the businesses. So, a person who can do different things smartly rather than doing one thing only would get more advantage finding a job. 

Lastly, there are no definite answers when talking about Humans and even businesses at times. I would say either you do what you like to do or if you do not like it you have to master it to like it. Further diverse background shows that a person is willing to go out of his/her comfort zone. If he/she managed to survive than there is nothing that would stop him to chase what he want. So, its his/her attitude that would be determinent of selecting a specific carreer for his/her better future.

Good Luck :)