Cousins are great if you stay close, but generally as you get older you drift apart and then you're left with no one again.
Anecdotally: as someone who was the youngest by 5+ years in a family of dozens of cousins, I feel like I got a little bit of both worlds. It was fantastic as a kid to be running around with the posse, but as I entered late-childhood that pretty much dissolved. Now, as an adult, I no longer see my cousins on a regular basis. We don't have much history beyond my 7th/8th year and they're not the type of people I would want to be friends with by choice. This estrangement was a big source of mental struggle for me throughout my early 20s, especially since I lost my actual sibling and didn't feel like I had anyone to relate to in my "supposed" family.
I almost think it's better to start off life with not much extended family, because it's not easy to make friends that you consider family when you're already a fully-fledged adult.
Anecdotally: as someone who was the youngest by 5+ years in a family of dozens of cousins, I feel like I got a little bit of both worlds. It was fantastic as a kid to be running around with the posse, but as I entered late-childhood that pretty much dissolved. Now, as an adult, I no longer see my cousins on a regular basis. We don't have much history beyond my 7th/8th year and they're not the type of people I would want to be friends with by choice. This estrangement was a big source of mental struggle for me throughout my early 20s, especially since I lost my actual sibling and didn't feel like I had anyone to relate to in my "supposed" family.
I almost think it's better to start off life with not much extended family, because it's not easy to make friends that you consider family when you're already a fully-fledged adult.