Simple bully logic. If you are bigger than someone else, simply hit and threaten them to get whatever you want. Works really well until all the victims gang up and fight back together.

Lawyer, friends/family, cloud storage, or safety deposit box all seem like viable normal options.

To be extra safe. 6 hard drives (each with a copy of the files, and four stacks of Blu-ray disks (each with a copy of the files). Divide these into at least two yeti coolers (include a large silica gel pack just in case), and bury the coolers as deep as possible in the woods.