Neither DW nor I have been diagnosed with heart disease and are in our 60s. We have, however, taken numerous CPR training courses. The consensus among CPR instructors is that an AED increases the chances of survival for a cardiac arrest victim from around 10% with CPR to around 70% with AED. Good enough for me.
We have one in our home, because we entertain a lot of guests. We take it on the road when we travel, whether in the camper or in the car, because, as the OP said, "...one just never knows." I don't think of it as being for DW and me, necessarily. I'd just like to be prepared. A life is a terrible thing to lose, whether it's mine or someone else's.