I’ve been doing track days for 20 years and have never gotten track insurance. I do think about it all the time, but typically decide against it. As you move up the run groups incidents become more rare, and I do believe that accidents are typically less likely on the track. If anyone is driving reckless they are removed, if anyone has a 4-wheel-off situation they are black flagged (and typically removed if they do it more than once), and there is usually lots of run off (yes, depends on track and corner, but a lot of tracks have some good run off areas). Track days are very much scrutinized for safety with eagle eyed marshals watching everyone all the time.
The group I see most incidents in is typically intermediate - more skill than a beginner, but also a bit more ego, but once you get to advanced everyone is usually very experienced and fully aware of their surroundings.
In all the events I go to, there are usually at least 100-120 cars in attendance, and maybe 1 “impact” incident, though many times none. Blown engines occur more often. So basically a 1% chance of an incident, but again, that incident is entirely dependent on group and experience.
Only once have I seen two people hit each other - and they were two friends who decided to try to race each other in Civic’s. They were removed.
Yes you can have an incident where a mechanical failure or something causes an issue, but it is rare, and can equally happen on the street (where it will probably be more dangerous with unpredictable road hazards).
Anyway, yes, insurance can give peace of mind, but also think about it - if accidents were common, would OpenTrack or Hagerty be in the business of providing insurance? They are, of course, hedging that the vast majority of people never have an incident over their entire track lifetime!