I'm a very independent and introverted person by nature, so solo trips are right up my alley. I do most of my travel solo, and Disney is one of the best places to do that since I feel so safe there.
I've had a couple group trips in the past few years, and while I have wonderful memories from those, they also stress me out. Navigating the emotions and moods of other people causes me more anxiety than the crowds, weather, and long lines. I'm not sure why, and it's likely something I should see a therapist for, but it can really weigh me down. Riding ROTR and Cosmic Rewind for the first time with my Disney-loving buddies are experiences I wouldn't trade for anything, but I've made a habit of carving out alone time near the end of each group trip so I can bask in my own company for a while.
I find that when dining solo, sometimes the wait staff are more attentive than when I'm in a group. (Not always, but often enough that I've noticed.) And while single rider lines are great, sometimes you even get to skip the lines at other rides when they're looking for smaller groups (Space Mountain, Tower of Terror, Soarin', Dinosaur, etc.) Not having to confer with people about what to do next saves a lot of time, and I've also left queues before because I just wasn't feeling it. I can also find a spot for parades and fireworks without camping out an hour ahead of time. It's glorious.
Every now and then you get a cast member loading an attraction who will ask "Just one?" in a way that makes you feel a little judged, but I've also had parents ask me to switch places with them. Do I sometimes flash back to a great memory with a friend and get a little nostalgic? Sure. But I do find that I post on social media more when I'm traveling alone. People from home, especially my Disney Buddies, will comment and respond, making me feel like I do have company at times.
Also, I've met and talked to so many people when I'm there alone. On the Skyliner, in queues, on buses. One morning I was eating at Les Halles, standing at one of the high top counters along where the line forms. Several very friendly people asked what I was having and what I'd recommend. It made for a lovely morning. I find that I'm able to live in and enjoy the moment so much more when I'm alone than when I'm with people. Breakfast in the parks is an especially great time for me, for some reason.
The trip report in my signature details the 10-day solo trip I took in August 2018. It was the best trip I've ever had. I've had some shorter ones since, and some group ones, but this one stands out above the rest. (Out of about 15.)
Anyway, I say all of that to say that solo trips are wonderful. They may not be for everyone, just like large group trips aren't for me, but I would highly recommend it to anyone who already enjoys their own company.