Doubt it is or only is adrenochrome. There are a lot of cutting edge and unapproved (and very expensive) life-extension treatments, plus other treatments for specific situations.
All those under consideration have personal assets that allow them access to such treatments....and not all are successful in every instance.
After all, Hawking is dead.
Hawking lived far longer than expected.
Only about 50 years after his expiration date.
He did live close to 20X the typical survival time post diagnosis. Probably more a testament to supportive care and his drive and fortitude though.