Well, any individual person can conclusively tell if they died of cancer. It's not so easy to conclusively for an individual to tell if their brain is getting

Well, any individual person can conclusively tell if they died of cancer. It's not so easy to conclusively for an individual to tell if their brain is getting generally "fitter", or if they're only getting better at the specific "exercises" they're doing. IOW, if you want to show up with a big bag of bills and expect support, you need something much less falsifiable.