I was kinda chuckling when I read this. I fly at home, on my own property, if I had to share the experience with someone else I wouldn't be able to fly. I'm regularly "Home Alone" LOL. If someone else is in the general vicinty of your flight you're just endangering another innocent bystander as well as yourself (just kidding here).
I used to go to the club field all the time and fly my airplanes when I was the only one there, never even considered it being unsafe. After 20+ years of flying "planks", never gave a second thought to trying helis on my own. It's completely within the realm of possibility that I'm just "safety challenged"!
In all fairness, I'm sure the suggestion to have someone around while you are flying is sage advice. Maybe just not practical for all. When I was learning to fly planes, having an experienced pilot test fly, and even better having an instructor to "buddy box" your bird was the fastest path to learning.
Today we have the additional tool of the simulator to help advance skills without the fear of losing a model. I started flying helis without a simulator, but quickly learned it's a far better alternative than a depleted bank account.