The Bigger the Safe, the Better
This person believes that if a safe isn’t bolted to the ground or if it’s small enough for one to two people to carry, then it’s not safe at all. Think bank safes. Now, they don’t have to be as large as a wall (obviously not everyone has that kind of space in their home), but they should be hefty enough that multiple folks are necessary to move it.
Bolting it down will also ensure that burglars cannot move the safe without utilizing power tools. Power tools are, naturally, loud. Thieves want to be as quiet as possible so as not to draw attention. So … draw attention. Make it a struggle for them. Make a statement to all robbers everywhere that you can’t be burglarized.