Well, keeping 1-2 BTC as a personal wallet for real-world transactions makes some sense. As for keeping ~50 BTC - a possible scenario is that the guy/gal bough

Well, keeping 1-2 BTC as a personal wallet for real-world transactions makes some sense. As for keeping ~50 BTC - a possible scenario is that the guy/gal bought a specific, cheap Android phone as a "safe" - that is, installed only the blockchain app, and cut off the internet/cellular connection. One would expect the phone being offline and the app being from a trustable source to be secure :)