Aam sorry OP you may have to correct your thread title to number of countries that are holding Bitcoin and not number of people as being mentioned there.
If we are to talk of numbers of people holding bitcoin, I don't think we can even have them all, except we choose a particular niche in doing that, maybe considering the whales and stating the rate they are holding, all in consideration.
You're right as I also figured the controversy of the Op talking about people that owns bitcoin but are giving lists of countries owning bitcoin. Even that of the data as instigated with the values owned by the bitcoin users at each country may be invalid because it can't be proven to be comprehensive because on daily basis there're enthusiasts transacting with bitcoin and so on buying and selling of bitcoins.
I wonder where the data of each of those countries with the rate of their acquired bitcoins is derived from because I'm sure it's impossible to gather the total number of bitcoin users and same time analyses total of funds they holds.
Oh, did we not know that there're hodlers who had acquired their bitcoins by freelancing and other tasks that earns them bitcoin for free without buying it. We also know that those holding their bitcoins for the long term would always hold their assets on the non custodial wallets and not one like the custodial wallets where they could have a summary of user's.