I always thought that overall you have a greater chance of crashing on the track than you do the street, most of which are harmless low sides, worst case is you have a bad high side. Air fence is becoming more and more common to see at tracks so is reducing the risk of hitting something after crashing. That said the risk of injury is still greater on the track IMO, and even more so when you are at race pace rather than track day pace. I would say that the chance of death would be greater by riding on the street on fast rides between gravel on the road, cars going left of center or even low siding into an on coming car or guardrail etc... Also on a track medical staff is right there to help out if something really goes south. I suppose whichever you choose there is a risk that we all take. I personally enjoy track more because you dont have to worry about gravel or cars or wildlife "for the most part". You can just push as hard as you are willing/able and can learn so much more about how to control things like spinning up the rear when coming out of a turn. You can also see your improvements via lap time and dont have to worry about tickets. Im sure you and other street riders have their own reasons for preferring street riding over the track.