I come across this article recently.
http://www.allsingaporestuff.com/article/chao-keng-god-how-i-forced-saf-release-me-serving-ns

I shall post some quotes from there

Before I start, here is to the people who say people who chao keng are pussies, hum ji, ball-less, etc. Not everyone is suited for the military. Not everyone is made for getting shouted at by sadistic superiors. For my case, I decided that NS pay of $480 was not going to cover my housing rent, my car installment, my food and my other expenses. I was not going to give up my freedom for a national duty.

I enlisted directly into HRI as PES E9L9 due to 'depression' (as diagnosed by IMH). I first started going to IMH a year before enlistment to build up a case to get a down pes. True enough, I got downgraded to E9L9 from A. As I only have a private diploma and O levels, being PES A will definitely make me a chiong sua man. To me, my business and career is more important than NS. We can leave the NS to those who aim just to be a mediocre person in life

So to all PES F hopefuls, I want to encourage you to take this path. It is a path more exclusive than OCS, as only a select few can actually attain this highest honour. Don't be fooled by what some people say about PES F people being unable to be hired. The world is your oyster. Even if no one wants to hire you (very unlikely as people in the private sector don't give a fuck about NS and would be happier if you had no NS obligations), start a business or carve your own career. Don't let the negativity of people who verbally abuse 'chao kengsters' affect you. Majority of this people have the 'just suck it up attitude' and are happy with a mediocre life. I'm not and I am sure you are not. I want to excel and succeed and challenge the impossible.

In the first quote, he gave all kinds of justification for him to wiggle out of NS. Frankly, our NS age is about 18-20. Having to pay housing rent, car installments at that age? He must be a very astute entrepreneur, which might really be the case, given that they way he get his PES F status is quite astute.

In the second quote, he describe how he feign depression to get a PES E0L9 status, and at the same time insult all those who don't do it. If everyone were to do this, I very much doubt that he will succeed.

The third quote is actually quite inspiring. He say that we should not accept our lot in life and strife to challenge the impossible and follow our dream. I would say that there are different kinds of dreams. You can dream to be a rich man by building a business empire, or you can dream to be a rich man by fooling people to buy your bogus product at a high price.

If I am his prospective employer, I won't hire him. If I am his prospective customer/business partner, I won't do any business with this person. He has shown a willingness to cheat and even go as far as to feign mental illness in order to obtain his objective. In mandarin, we call this 装疯卖傻。 With such a major lack of integrity, there's no telling when he will give you a stab in the back if it furthers his agenda. We sometimes cut corners to achieve our objective, but a line has to be drawn somewhere. Not all corners should be cut. I am able to work with someone who jaywalks. I am probably able to work with someone who beat the red light at traffic junctions. But I can't work with somebody who beat the red light at traffic junctions, hit somebody, and runs away.

There are things to learn while doing our National Service, like working in a team, managing subordinates, getting fit, etc. I've also made valuable friends while in NS as well. It can be argued that we don't need National Service to learn those things. But since it's here to stay, we should make the most of it and not run away. And if you really prefer to run away, at least do it with some integrity.