Image taken from http://ascb.org/where-will-a-biology-phd-take-you/
There are numerous articles like the one above highlighting the disparaging fates of science PhD graduates. Indeed, many PhD students I know, myself included, have often been mocked for a decision to commit several prime life years in the noble pursuit of expanding scientific knowledge on a basic stipend with a definite promise of working weekends. Do not kid yourself, it is a large investment, so why the hell should anyone do it?
Here are some good reasons to do a PhD, with some bad reasons thrown in for good measure:
1. Good reason: To progress more rapidly in my scientific career. Unless you want to remain a lab technician for the rest of your life, you need a PhD (ok, MAYBE if you have a boss that recognizes your scientific prowess and fights for you, you may progress to senior scientist level without a PhD, but it will take a looong time and may not be easy). This applies to jobs in scientific research be it in academia or industry. It also applies if you want to make more money as a technical expert, for example by becoming a field application scientist. However, if you want to do sales and marketing, a PhD is definitely not a requirement, in fact, it may even be a hindrance.
2. Bad reason: It’s the only thing I can do for now. This is the reason I sometimes get sick of hearing. It just goes to show you have not TRIED anything else. I did not know I wanted to do a PhD. I only knew I wanted to work in science. So I tried a science job. I liked it, and I knew then that I needed a PhD to progress. If you are in a science job, and you like it and you want to grow better at it, do a PhD. If you are in a science job which you hate or feel apathetic to, but cannot think of what other jobs you can do, do NOT do a PhD. If you have just finished school and do not know what to do, do not do a PhD. It will only make matters worse. Try applying for jobs of some interest to you, it will be easier to get them if you do not have a PhD than if you did. And you would have saved a whole lot of time and heartache.
3. Good reason: I am really super duper interested in this field of study. Doing a PhD can sometimes actually be a privilege if you are in love with what you are studying. Imagine waking up everyday and doing something you are deeply interested in and getting paid for it, with flexible working hours. Not too bad a life huh? Be careful that your field of study has actual people working in it though, you do not want to be working in a vacuum where you have no one to learn from or share your findings with. And depending on your needs, give some thought to what you might do after the PhD. If you choose to study something really niche like the fecal-eating habits of the sub-saharan anteater, make sure you learn from the best so at the very least, you can be reliably considered one of the experts in your field.
4. Bad reason: I want to make more money. The honest truth is, scientists do not make a lot of money. If you want to make more money, be filthy rich etc., be an investment banker, an insurance agent, a real estate agent…. go into sales for goodness sake. Stop thinking a PhD will automatically leave you rolling in dough! There is more to it than that. If you are stuck at a postdoc level, you will be getting SGD$55-70K per year. A senior scientist may make slightly more than that, but you will definitely not be hitting the $100K mark unless you were in some managerial role, which takes more than just a PhD to obtain.
But that shall be another story for another day.