But it should be clarified for the OP who is a newbie that these are statistics on addresses, and that a person usually has their holdings in several addresses, so it is not useful for anything more than getting a vague idea.
I also wanted to quote this distribution. According to it, if you're holding anything over 0.1 BTC, you're practically in the top 10% of holders, at least in a way. 0.10 BTC isn't a great deal of money, but it's a relatively decent amount of BTC for the average person interested in cryptocurrencies. However, I agree with your point; the majority of people are holding their coins not only in separate addresses but, most importantly, on exchanges. The majority of daily transactions occur on centralized platforms, so it's quite safe to say that, for this reason, it's practically impossible to come up with accurate statistics on how much BTC is averagely stored.