I vaguely remember reading an article(as an online pdf - possibly via twitter) on why one should/should not do a PhD; what doing a PhD entails. It was well structured and specifically mentioned that a PhD isn't for everyone. I also remember it was written by a prominent computer scientist(or a mathematician). Can anyone provide suggestions/hints about what article it might've been?
Here are some sources I have found that speak to the topic of not getting a PhD.
Perhaps this document is the one you are looking for? Both the authors are mathematicians with PhDs. I would not say they are necessarily prominent, but they are established.
This is a short article reposted by a professor at Stanford University.
Here are three other online articles about the topic.
I will add my own brief commentary here. Obtaining a PhD has never hurt me financially. I have a well paying full-time job that requires a PhD. (Now should the job require a PhD is a different story). There are many, many, many jobs in my field (statistics) that prefer a PhD. I have never regretted obtaining a PhD.
Philip Guo writes a lot of advice, including an e-book about earning a PhD.
Perhaps Teach undergraduates that doing a PhD will require them to embrace failure. The author is a molecular biologist, not a mathematician.
Perhaps this short "Illustrated Guide to a Ph.D." by Matt Might? It's a personal favorite of mine. He is a computer scientist but there is not much advice about why it's not for everyone. However, it's worth a read regardless.
I have found the article I was looking for, here. Although the author isn't a popular computer scientist, I did find parts of it quite useful.