Anyway, thanks for sharing. This is not exactly an obvious fraud.

I think one way to prevent it, aside from remembering to not let your SIM off your hands is to mark/paint your SIM and make it unique and easily recognizable.

Then you can deal with it immediatelly, even if you forget the rule to not give your SIM temporarily to others. (You'll probaly not forget, but people who may not have your experience and still want to protect themselves against this, may.) Also the attackers will not probably attempt to swap unique looking SIM in the first place.