If you have time on your hands which is basically free for you, and you run the relay at home too, there's no extra cost involved. You don't need a VPS to run a (non-exit) relay. Even if you do, the VPS will be associated with you much more directly than a third party exit, which is unlikely set up to log IPs. The VPS IP might even be publicly associated with you, if you use it e.g. also for web hosting. And Tor allows you to pick the exit location, like VPN services often offer different locations.

And could it possibly be that people exist that do things for pure enjoyment of the exercise? Looks like they learned quite a bit throughout the process. In practical terms, this may even land them a job at Tor (or elsewhere) later, since they can demonstrate that they understood what it is doing and where to find the relevant pieces of information to "circumvent" the protection.