Some of the loneliest people I encounter are actually couples at excellent, romantic restaurants. Yet each has their head down staring at a "smart" phone with a dull, lifeless expression, zombie scrolling. Indeed "Life" around the world has changed for most, loneliness is a growing epidemic, especially with the youngest generations. Just another reason I don't own one of those NSA tracking devices ...
As the old saying goes, Know yourself. Many people cover up loneliness with meaningless socializing that then leaves them feeling empty afterwards, never getting to know others and themselves better due to not being Real. Being a solo trader can FORCE one to become Real!
I spend quite a bit of time in deep wilderness, physically alone, but not lonely, instead filled with awe and gratitude. One year I went to Alaska with a 105 LBS pack, a large caliber gun and a camera bag for weeks. When you really Know yourself from pushing your limits to the max, (similar to trading), and facing wounds and overcoming weaknesses, and are at a deep peace with your inner self, it is much harder then to be lonely.
I have a handful of True Friends I can trust with my life, and we truly know and trust each other. One is like a daughter to me. When I am finished with trading for the day or the week, I can touch upon some of my solo "market wilderness" experiences with them, and then to some degree they understand. And all of them are people of strong character, which experience has shown me is necessary for long term success in trading. You never know, maybe I will team up with one or two of them in a trading venture down the road... either way, I would not switch trading Futures for a "normal" job working with others again, mostly to be around modern people, no way!