I get a kick out of ones who say they have never had a problem. In the last 30 years I have not had to put my spare tire on my car. So I guess it is a waste of space and money to carry a spare.
I bet the last person to have something stolen today probably would have told you yesterday they have never had a problem.
I lock my hitch mainly to prevent 8 year old rug rats from messing with it. My Niece had their 8 year old pull the locking pins on a Reese slider. They had some interesting towing as the trailer slid back and forth at the first stop sign.