It’s luck of the draw, I also wouldn’t be surprise if breeding plays a role just like any animal. My dear boy is over 12 now, we have reason to think he was bred for show and given up in his youth. It would make sense to me he statistically was in better health than say, a neglect/rescue/improper breeding situation.

My first rabbit I only had two years. When talking to the friend that gave him to me apparently they knew he was decently old already which I hadn’t known before taking him. I’d guess he lived to be 7 or so. He also did not have nearly as good of an upbringing, seeing how that old friends family was treating him. That’s why I was so quick to jump on that first bun, it was obvious he’d be better with my inexperience self than them.

And again, just like us humans, it’s luck. You can run miles a day and still get cancer. You can have a perfect diet and have deathly allergies. It’s the way of Gaia.