Havard’s NPC lists the following net price to parents with typical assets:
$65k income – $0 cost to parents
$100k income – $5k cost to parents
For families with incomes that are less than double the US median household income like this, it can be difficult to match Harvard’s cost after FA, even with merit scholarships at other colleges. That said, yes the 90% figure includes all families in the US, not just those who are accepted to Harvard, and those accepted to Harvard often are eligible for quality merit scholarships elsewhere and often have high incomes.