Does my age matter?
The point stands on its own.
There are a significant number of people in the world that leave their vehicle unlocked with the key in the vehicle and that have not had their vehicle stolen. Does the simple fact that a vehicle hasn't been stolen yet mean that the method of storing it is "secure"?
Honestly, that's a perfect argument.
You are stating that your brainwallet is proven "secure" simply because it hasn't been stolen yet. Meanwhile many people with brainwallets have had their funds stolen.
I'm pointing out that a method of securing something that results in some losing what they are securing, can't be considered "secure" just because others haven't yet lost what they are securing.