It’s really best to think about a PhD as an apprenticeship to run a research lab. If you go into it with that expectation, you’re not bound to be disappointed. Any other perceptions may leave you a bit disillusioned.

The true value of a PhD is that you get to spend about 8 years or so learning under the close tutelage of a distinguished individual in some field. And really, that’s how you should pick your program — more than the school or the program or the research topic, you have to pick a researcher you want to work with; your brain is going to end up working a lot like theirs by the time you defend your dissertation.

Because what they are going to do is teach you everything they know. It’s incredible, you will feel like a novice at the beginning, but there comes a point a few years in when you realize that actually, you know about as much about this topic now as someone considered an expert in the field. In fact, you are writing their papers that they are publishing. And actually, you disagree with some aspects here and there. Then suddenly, you start having ideas of your own, ideas that you know no one else has thought of before. So you write them down, and that is how a researcher is born.

At this point the idea is that you are kicked from the nest and you will set up a research startup at some other university. This is much like running any other startup but the product is research papers and the revenue is federal grant money.

So to the questions at hand:

1. Are there skills you learn during a PhD that you can learn elsewhere?

Of course. And maybe sooner. A great deal of time is spent on the dissertation. You may have acquired the necessary skills only a few years in. Many people in CS acquire these skills outside of a PhD program (and wrongly assume they have therefore obviated the degree entirely).

2. What are the opportunity costs of getting a PhD?

Well, quite a lot of money although not as much as you think (due to stipends and tuition remission). But there is a lot of financial upside afterwards depending on the field. But I think if you look at peer groups in their early 30s, PhDs would be on average much poorer but some ramping up to much higher earnings.

3. What are the opportunity costs of not doing a PhD?

You will be locked out of some opportunities for good. Or at least, a PhD is an easy way of unlocking some opportunities. For example being an expert witness. It’s easier to immigrate to some countries if you have a PhD. It’s easier to get visas. There are certain grants you can only qualify for if you have a PhD.

Also people treat you like you know everything about everything. This is a blessing and a curse, because if you’re like me you are wrong a lot. Then people will make remarks like “you have a PhD? How do you not know this?” The flip side is your relatives will love to brag about it and it will make your aunts very proud to tell their peers.

And finally, there is really no other way to get that apprenticeship experience. If you really want to get into a topic, spend the better part of a decade obsessed with it, with no other responsibilities or distractions, then I know of no other place to do that than a PhD. Some startups could be close but really would need a lot of funding and be okay with little to show for 7 years. I don’t know many investors that would be cool with that but maybe there are.