Should public sectors be privatalised?

Your question betrays that you are making a lot of assumptions that you are not stating. Because nobody ever realizes they are assuming so many things, arguments never end.

You assume there is a public sector, a private sector, a business sector, and a government sector. You assume that all those sectors are basic parts of the universe, even though they are created by people. You assume they can not be changed, even though people make changes constantly (your own question proposes a change).

Many people have examined these assumptions, written books, even earned degrees. Many of those people write regularly for websites, fee.org or mises.org or downsizedc.org, and many write columns of financial advice at gold-eagle.com and gold-silver.com and many more. So the answer to your question must be drawn from those essays and books because you need supporting material along with the simple answers. That goes along with another common assumption, that the world can not operate without all those clearly separated sectors forcing people to do what has to be done. The disproof of that assumption is found in a free ebook at comingdarkage.blogspot.com/

Your question has a short answer, but it takes a lot of study before you can appreciate it. The answer is "The only way to win the game is to refuse to play."