Anecdotes like this are unfortunate I guess there will always be some bad actors out there only focused on themselves. That said, its not the norm from what I've experienced.

I do try and gauge the local vibe before leaving any of my equipment unattended. I'll also observe what the neighboring sites are doing to get a feel too. At times, I'll also chat with other campers and get their opinion, and make them aware of my circumstance.