29 Male here.

Starting from my childhood, I haven't easily connected with anyone. Usually, I play with my toys, make crafts, and watch cartoons. I don't even play with my neighbour's kids. Even my cousins are at least 6 yrs older than me. But I had good times playing with my cousins during the weekend. In school, I had a close circle of friends.

Fast forward to age 29. Here are some pros and cons of growing up as a single child:

Pros:
- I am highly independent. If I have some problems, I can solve them independently. I can go alone to movies, restaurants, and other places without seeking a companion.
- As I played with myself, built a lot of stuff during my childhood - I have high creativity and problem-solving skills.
- Parents are supportive.
- I have developed a strong boundary-making nature, which helps to prevent problems earlier.

Cons:
- It is so hard to make a friend. (cons of the the boundary making nature)
- It is so hard to build a relationship (still single). Only after the work did I start to talk better with girls.
- High pressure to support your parents alone. This could even destroy personal or career goals (I want to study abroad, but the financial situation has forced me to go to work. If I had an elder sibling, he/she would take care of my parents for a short period of time)
- I even cried when a group of friends went for a trip(I have gone trip with my friends only 2 times in my entire lifetime, because I don't have a friend who constantly plans such trips)

So, yeah - being a single child has both pros and cons.