All the precautions assumed are good ones and I do them.

I hike alone most of the time. My former companions have been taken over by their children's soccer leagues.
So if I'm not willing to go alone I'd nearly never go.

Hiking with someone isn't an automatic good deal. If you and your partner are matched, or your partner is smarter/fitter than you it's good. But if your partner can't be counted upon to be sensible and a true partner then you might be better off alone.

Some folks will not be able to help you when you need it. Some may invite trouble by doing stupid things that you wouldn't do. (climbing stuff, jumping stuff, wading water, etc)

And there is the phenomenon that the bigger the group, the dumber the group decisions ("hey, if that doesn't work the group can carry me out, right?")

I fired a guy as my hiking parter because he had no more responsibility for the outcome of the day than his Cocker Spaniel. I decided I was better off hiking alone than hiking with him. (He took it to heart and got some training to be a Sierra Club trip leader.... )

Hiking alone isn't perfectly safe. But neither is painting your house, walking the dog, or driving to Grandma's house.