I bought my first truck camper sometime around 1975. Since then, I have owned a camp trailer, a travel trailer, I lived in a fifth wheel for three years, I have owned 4 different Class A motorhomes, one Class C motorhome, and a couple of other truck campers.
I have never met anybody who lost a trailer of any kind while moving. I have never met anybody who lost a towed vehicle. I have never met anybody who dropped a fifth wheel on their truck box. I have read about one instance where a trailer on the freeway got away from the towing vehicle (it was on the wrong size ball, no safety chains were in use, and there was no breakaway brakes in use).
Having said all that, I use safety chains on all towed rigs. They are attached to the receiver safety chain loops. I have never needed them, but they are there, and hooked up!
Safety chains or cables should always be connected in front of the most likely failure point on the towing vehicle, and behind the most likely failure point on the towed unit. ANY damage to the chain or cable is cause for replacement! Remember, "A chain is only as strong as its weakest link!" A damaged link is a weak point. the same applies to cables, even though a cable has no links; any damage weakens the cable!
CM1, USN (RET)
2017 Jayco TT
Daily Driver: '14 Subaru Outback
1998 Dodge QC LWB, Cummins, 5 speed, 4X2
2 Kawasaki Brute Force 750 ATVs.
Pride Raptor 3 wheeled off-road capable mobility scooter
"When seconds count, help is only minutes away!"