TLDR: Low overhead and no need to really make any profit.
As someone that has been involved in the planning of PCA track events for many years, I can shed some light on this. PCA was one of the first to the game, and most other track day groups have origins with the PCA. My club actually held the first DE at Mid Ohio in the late '70s, and it was a huge deal for them to allow such a thing. Right now clubs are making small fortunes on events that they have planned on just breaking even on. Four years ago this was not the case. We were teaming up as regions to reduce risk.
PCA does offer some pretty affordable and good event insurance. PCA events are run at the regional level by volunteers. The overhead cost in these parts is track rental, insurance and occasionally a couple hotel rooms for the registrar and the event chair. Dealerships often come in with sponsorship of t-shirts and a dinner. Lately we've been having the mid ohio school supply some of their instructors for the weekend for advanced instruction (at no additional cost).
Instructors have to pay a very modest amount these days, but its really just something they came up with to piss off some instructors that were taking advantage of the free track time.
Some regions host PCA club races. These are really really hard not to lose money on, but that is another topic for another day.
At the end of the year, the goal is to just have enough money in the bank to have some nice parties and have the deposit for next years events.
