The fact that you resort to maths to even try and prove 9 out of 10 people don't know a cultural icon from the last 50 years is embarrassing.
Embarrasing? It's just the way it is. Not everyone knows the "icon", and that's perfectly fine.
The people on the high horses are those who chuckle or find it strange when someone doesn't know their "icon".
Entertainment (and pop culture) is indeed a big bubble, but it's still a bubble, and there are A LOT of people who are not in it.