Recently I had a conversation with some new and some old friends about traveling, and everyone seemed to be saying they were thankful for their travel buddies and couldn't imagine going at it alone. For me, someone who's always traveled alone except for a few day to 3-day trips around Europe, I don't really give traveling solo a second thought-- this is what I'm used to, so that's how it is. But now I'm really thinking about what's great about it, but also what could be better if I did have a friend, family member, or significant other by my side while traveling.
The main thing I love about traveling by myself is the freedom. When I'm with people, I tend to spend a lot of time in my head thinking "are they having fun/would they rather do something else/am I showing them a good time," and I hate having those thoughts. Usually, they are in fact having a good time, and then I've wasted mental and emotional energy stressing over non-existent problems. When traveling solo, you make the rules: you decide when you get up, what you do in a day, how much time you spend at Zara, how many episodes of Queer Eye you binge on Netflix at night (go watch it now, seriously), etc.
Also, after age 3, I grew up as the only child in the house, so I'm very used to making my own fun and not always having (or even wanting) someone to hang out with. It's a comfort level thing, I think. And while traveling to countries where I don't speak the language, I think I revert back to what would be most comfortable for me personally. So, if you grew up in a big family or are 100% an extrovert, you might really enjoy traveling with someone way more than going at it alone.
The pits of traveling solo? There are definitely a few. One I noticed while I was waiting for my flight from NYC to Italy a month or two ago, and that's just the fact that you have someone to lean on. I witnessed couples helping each other with their bags, friends looking at their boarding passes and together figuring out what direction to walk, families laughing and slowly making their way to their destination... it was all very sweet to watch, and I found myself thinking "... well this sucks for me!" My main want would be having someone help me with my bags, honestly. I packed two 50+ lb suitcases to come here, plus a carryon, plus a purse, and that's my usual load while traveling from place to place.
Having someone to help lift things onto trains, keeping an eye on everything, help navigate, etc. would be really great and helpful. However, not having that and getting where you need to be on your own is pretty empowering! I feel very confident now with my sense of direction and with simply trusting my instincts. That might seem super simple and insignificant, but when on your own in a foreign country, they're actually pretty important.
Overall, I'd suggest at least giving solo travel a shot. Even if you're an extrovert, traveling on your own might give you a boost of self confidence you never knew you needed. And, if you absolutely hate it, you'll know to always have a travel buddy with you after that!