How are you going to protect the safe? If you bolt it too a wood floor, they will chop out the floor and haul the safe away if they can't open it. If you anchor it to the concrete floor in the basement, it might get flooded sometime - or mildewed and spoil the contents.
Maybe a safety deposit box at a bank would be safer for important small stuff - and a really good hiding place for the larger stuff.
My wife's opinion is: "If they are determined to get you, they will!"