Dog is not the cheapest option. The amount of work that goes into taking care of a dog is quite substantial. I know from experience. While many/most people do not mind doing the work/expense, some of us prefer cats because they are a lot less work, among other reasons. I do however admit that cats suck at scaring away intruders.

Best and cheapest option is a dog, decent insurance, and off site backups that regularly get restores tested.

And maybe a little bit of not getting too attached to "stuff" - there's very little stuff that's truly irreplaceable. I'd miss my first guitar if my house was robbed and they took it or if my place burnt down. I'd miss the HiFi gear I bought in 1988 and still use, and maybe my modded espresso machine. But I'd get over that loss and my sentimental attraction to those things just fine, especially after I'd replaced then with my insurance settlement.

Most of the world don't construct their homes out of flammable materials, so the risk of the entire place going up in flames is quite low. In some places your home is uninsurable if you dont have burglar bars on all windows.

Regarding dogs: some organophosphate mixed into minced meat and lobbed through your fence/gate/open window is an instant and quiet way to get rid of a dog - personal experience taught me this lesson.

Or "diversify", basically don't put all of your eggs in one basket. Can be done at any scale too, from storing backup copies of important documents at your parents house to buying a few apartments in Indonesia.