I play solo all the time, but I have made friends on the server I play on, specifically the admins :P
But even before I made friends with the admins on this server, I played on a number of other servers as a solo player and have gone after bases and groups of 6-8 players with hit & run tactics, held my own, raided bases and died very few times.
And my base is pretty far away and well hidden with many defensive tactics like logging off away from my base between some random rocks with all my valuable stuff on me, plus my base being low and wide, using 1x1 secured rooms that force players to use plenty of C4 to get anywhere.
Yes, it is more challenging as a solo player, but I love it.
I don't have to rely on others and I don't have to share my spoils or my resources.
Once in a while I will ally with others and help them out for a common goal, but other than that, I roam on my own and use stealth to my advantage.
Am I on the top of the food chain of the server I am currently on?
Not exactly, as the admins have a much bigger base and much more going for them than I, but I'm in the top tier of the food chain and I'm quite happy with my current position, all things considered.
I don't ask the admins for any special treatment or help, meanwhile everybody else on the server is constantly asking them to give them this or help them with that, or switch it to day time (annoys the living hell out of me because I like the night).... and that's another reason why the admins like me.... I don't ask for anything, I don't mooch, and yet I will help them with trouble makers when they need a contractor to keep their distance.
Playing solo is the best because the rewards are higher, as well as the stakes. When you succeed, you feel a hell of a lot better than when you have to share your victories with others.
Even when others don't know I raided them or did something amazing, I know I did and I play for myself, not for others.
but it is more boring if you don't talk to anyone