I seem to be late to the party, as always
I don't think that what people are saying about large families is exclusively just large families.
I'm the youngest of 3. My siblings are both nearly a decade older. I was lonely as a child, probably because my siblings were too old to be bothered to pay any attention to me, and I think my parents were bored of parenting by then. I rarely spent any time with them - I was usually told to go to my room/outside or to go call for xyz to see if they'd come out to play.
We weren't poor, not rich but not poor, but there certainly wasn't many treats (very rare), new clothes (only when I grew out of them, and I had no say in them. In fact, I don't even remember getting new clothes, or even shopping for them) or day trips out to places (about once/twice a year, if that) and definitely no holidays. And I definitely had no privacy, my brother walked in to my room at will and I shared a room with my sister.
I'd have loved to have had more siblings, especially ones closer in age to me - in fact I used to ask my mum, especially during my early to mid teens, repeatedly if she was going to have any more (I knew it was almost impossible by then. She was mid to late 40s by the time I was a teen, and had had her tubes tied) but that didn't stop me hoping!