Being formally single id say the only downside is that when you only have yourself to take care of, in this backwards society that shows how insane it is, to the point even the most useful things in life like tech and medicine still seem to be a hindrance under the wrong powers, you may start to look at life as almost pointless and mundane.
Even if you switch up your routine, you don’t have a constant, new perspective in the house challenging you, embracing you, daring you to step outside of yourself by loving and teaching them.
I’m having my first kid soon and when I see other people my age with their little babies I get very excited thinking about how I’m going to love him/her and teach them what they need to survive and succeed. When I was just solo tho I was getting to the point that if I didn’t accomplish anything by like 30 I would abandon my family and be a monk somewhere due to shame
Not everyone feels that way of course, but I was extremely pessimistic before and in hindsight, extremely slothish and greedy because all I wanted to do was sit on my ass and get rich off crypto and stocks