My iPhone is the least valuable thing I carry. But I didn’t realise that until my iPhone was stolen (pick-pocketed in Barcelona).
The thief didn’t get my keys, passport or wallet. If he had taken any of those items then I would have been unable to start my car, unable to leave Spain, or unable to pay my hotel bill.
Instead, he stole my iPhone4, which basically meant I couldn’t call, email or tweet. Within three days of the theft I was using a replacement iPhone5 (free upgrade from O2), and all my family photos & apps were restored from an iTunes back-up.