I just looked over my entire collection. There are only 2 games I bought from people I didn't know. And for one of them, I brought a friend with me. The other one was only a $700 deal, so it wasn't a big deal.
I can't remember the last game I sold to someone I didn't know. I almost did a couple weeks ago, but a friend knew them. Plus when they arrived, they recognized me immediately because I had met them a couple years ago (nice people).
It's all simple. Keep yourself safe, and if you don't feel safe, don't do it. Just listen to that inner voice, and when it says "danger", stop what you are doing. Let people know where you are. Take pictures on your phone that go to your cloud account. If there are cars, get those pictures of all license plates into the cloud.
And really, if someone tries to rob you, give them the money, then call the police when you're safe. No need to die over a little money.