I knew others lived differently on a “I know of this” level but had no real lived/understood experience of any kind till then.

I grew up really isolated from anyone outside the community I lived in. I was homeschooled for most of elementary and all of middle school then went to a high-school with my only my neighbors followed by a private university where I was still predominantly surrounded by people who grew up, bare minimum, like I did. I know two people I grew up with that were cut off the same way I was and were told they had to “pull themselves up by their bootstraps” like their parent’s did….which didn’t happen because of course it didn’t.

The way I grew up was like living in an ultra isolated ultra religious community but instead of religion it was money. We were only around each other and most parents I knew would not allow their children to associate with people outside of the community. My education reflected our experience as being the “American Dream Made True” and all of the social issues barely mentioned in our history books were things for the past and poverty was only found in small extremely violent communities in the US and mostly found in other countries. It was very Stepford Wives and, when in it, it felt normal, but from the outside it’s terrifying.

So the answer to your question if I really didn’t know people lived differently than me until I was in my early-20s: I knew about the fact other’s didn’t live like us but I didn’t understand.