In Memoriam - Dirk Cotton 195? - 2021

Dirk Cotton, one of the great retirement bloggers of recent years, was not really a close friend or an accomplice in Ret-fin crimes. But I did know him.  Here are some of my memories. 

I came to the retirement-quant world by way of a nexus of anger, fear and curiosity, of which Dirk shared the sentiments of all but the anger and maybe not the fear though he did mention that once.  Anger for me because of the prevarication and avarice of my Wells Fargo bankers who were going to charge me four grand for what I now realize was a Monte Carlo Simulation, a simulation that I knew I could - and did - recreate on my own (in excel at first, boy did that run slow). Fear because when I finally did my own calcs it dawned on me -- at a time I still valued risk of ruin more than I do today -- that my risk wasn't "80% chance of success" that the bankers had said but more like 20%. That was a big wake up call at ~52, about the same age Dirk retired, an age with really long horizons...or so we thought. Curiosity because I now wanted to know more about retirement math. In the end I wanted to be able to see, at an intuitive level, the ebb and flow of retirement math and process. And it is really this that Dirk and I shared. In the first sentence above I wanted to call him an "amateur" like me but he was a CFP and had a moderately monetized blog if I recall so not really an amateur. But his spirit of diving in and following his nose had the heart of the amateur: curiosity takes you where you will go. 

I still hadn't heard of Dirk though.  At some point I read some paper or article, long forgotten, where some dude named Dirk Cotton described how he had modeled a simulation of retirement in R. My first reaction was "what's an R?" Heh. My second was that if this guy -- I think he was pushing 60 at that point -- can write a program in R, I certainly can as well too (I teased about that once). So, I taught myself R the next day, and re wrote my MC sim in an afternoon, even though we both had a skepticism about Monte Carlo and the concept of ruin. That coding self-ed, though, launched me into an extremely explosive productivity leap since the capabilities of R were relatively unbounded where Excel (and VBA) is constrained. In the intervening time I've had the opportunity to build all sorts of stuff: a backward induction engine, a consumption utility simulator, and a Reinforcement Learning algo, among other things. Hat's off to Dirk for the nudge. So, now I knew this "old guy" who'd learned R and was into retirement analytics. I paid attention thereafter.

I followed his blog and I read his articles. I even paid for some of them, something I pride myself for not doing because I can usually find papers by hook or crook and so ignore those I had to pay for. So far I think I've only paid for Cotton, Yaari, and books by Moshe Milevsky. Good company!  I saw the work he did with his son on "conditional something or other." I saw some of his collaboration with an UNC econometrician.  I saw him explore chaos theory. I saw him shift from abstract modeling to more real world analysis.  In the middle of all of this I struck up a correspondence. This is the nice thing about the Ret-fin world. Over eight years my curiosity forced me to reach out to whomever: bloggers, academics, advanced professionals, etc. Invariably -- with two exceptions -- everyone wrote back.  The difference was that Dirk came across as unusually congenial.  He was the consummate southern gentleman -- a term that is probably forbidden now -- as if he were straight out of a Walker Percy novel.  

A few years later (maybe 2 years ago), since the woman I was seeing had a second place in Raleigh and since we were visiting, I emailed Dirk and suggested a meet. "Of course! Let's have coffee." So we met in Chapel Hill. The location was Caffe Driade, just off East Franklin Street northeast of CH. It was one of those eclectic settings adorned with wood and artifacts and surrounded by southern pine. We sat, drank coffee and shot the breeze. 

What did we learn? Well, for one, he was just as gentlemanly in person as in correspondence and articles. We learned we had a similar life trajectory: tech background, early retirement, curiosity about finance, similar age, kids younger than typical for men our age, same hair cut ;-). We learned our motivations were more or less the same. We learned that retirement quant blogging is basically not monetizable. We learned that our early retirements were rudely woken up at some point by the high cost of health care and children in or entering college. We learned that we both thought that mathematical ruin in the technical sense is kind of bogus in the real world.  I learned that he was actively moving towards simplicity and real world data where I was still making things complex and going abstract. I learned that he was like a humble king: people kept approaching him and acknowledging him as if he were at court. Certainly he was a regular but it was more than that. Respect, perhaps. Friendship. You know the type.  It was non-stop but never intrusive. An easy person, in other words. 

So, I didn't really know Dirk but I kinda did. I appreciated the connection. I was looking forward to more of that. I was looking forward to some of his new econometric work, too. Maybe there was even something we could have worked on together, idk.  His work on Chaos was of interest. It had spurred me to explore my own modeling of chaotic shocks to retirement in the form of unpredictable magnitudes of destruction like forest fires, earthquakes or sand pile avalanches (just consider divorce, for example. How often is that modeled?). That might've been rich territory. Maybe I just envied his ability to get his pretty darn good work published.  Who knows?

In closing, while I didn't know him well enough to really call him a close friend (a "friend" is enough, perhaps) there is most certainly one thing that I can say, other than that he was a pretty good guy:

Dirk died too soon.