Unique addresses.. Of course one person can have 100 addresses under his xpub with a few satoshi (why), but it's all about statistics.

Personally, I think the average bitcoiner needs around 10 UTXOs with different amount that are continuously renewed (noKYC, KYC, HODL, savings, entertainment, for LN wallet, etc..).

I think there are more than 10M people holding >0.01 BTC, because smaller amounts are not worth distributing too much among other UTXOs.