I started the PCT solo, it wasn't long before I latched onto new friends. I wouldn't "stick" with them, but sort of run into them from day to day.
The last month of my hike I found myself very alone. I was behind the pack and had several 3 to 5 day sections where I didnt see another human. It was great. Spookey stuff is reading Mountain Lion warning signs about recently spotted lions. "Don't hike alone" advice on them. Heh, makes you think.
Of course I was never lucky enough to spot one, nor did I have any trouble. As I knew the season was ending I was very careful crossing streams and glaciers. Knowing a bad fall could keep me there for days if no one wandered by.
Hiking solo might add more risk, but also adds more reward. Of course you have to be a "solo" kind of person.
I spent several nights alone sailing through the carribean and can't think of a better place to be.