Of course noting is 100% foolproof. However, I would prefer to take my chances with a big safe up a spiral staircase in a house at the end of a small one lane cul de sac which would require a vehicle to be taken passed the other houses by the thieves, where neighbours would be watching, than to put in a small safe and know that any thief can take it from the wall or the floor and carry out across the farm fields quite easily.
Thieves can and will take anything, but put bars on windows, alarm in the property and a large safe upstairs and you have a better chance of not being burgled than by not taking any precautions. As I have been told by the police in the U.K. thieves always look for the easiest in and out option.
I also think that if you rent out a property( we don't) you should take out all these precautions to go some way to protect the tourists paying rent. I am reading more and more complaints on T.A. from renters of holiday property whose holidays have been ruined by thieves, they complain there where no alarms, no bars and a tiny safe in a wardrobe that was just ripped out and taken. They also always go on to point out the Turkish Police where not interested. There are more and more of these complaints with people saying they will not return to the area and warning others not to rent.
If you rent your property I think you need to reassure you renters that you are taking all reasonable precautions that go towards them having a safe and happy holiday.