Historical Flammel also has an official grave site in France (Paris, if I remember correctly); I want to think he lived to his eighties, but it's been a few months since I last read about him.
I recall hearing that "grave" does not contain a body, although I'm not sure how the person who told me that knew. (They were suggesting using him in fiction, much as HPMOR did.)
Wireheading. The term is not a metaphor, and it's not a hypothetical. You can literally stick a wire into someone's pleasure centers and activate them, using only non-groundbreaking neuroscience.
It's been tested on humans, but AFAIK no-one has ever felt compelled to go any further.
(Yeah, seems like it might be evidence. But then, maybe akrasia...)