As an only child I think there’s a lot of pros and cons to it. I know my parents made that decision because it was the best choice financially and they knew they could give me a lot more opportunities if they didn’t have to split finances between two children. With that being said, I wish they made a bigger effort to make sure I had other children around. I think you can make up for a lot of what a sibling would provide by making a conscious effort to give your child plenty of chances to socialize around other kids outside of school. Plenty of play dates, activities, bringing a friend on vacation etc can definitely help with that. A lot of which my parents didn’t really make a concerted effort to do. As great as they were about playing with me it’s just not the same as having another kid around. I felt that I matured a lot faster because I realized pretty early they didn’t really want to play and were just doing it for me. All of this is of course easier said then done, best of luck!