This number is as irrelevant as misleading since a user can create an arbitrary number of wallets. Even if each wallet matched one user exactly, this figure still would not be of great help since, first, we can't see how it changed over time, and, second, there might be a lot of abandoned wallets of users who are no longer interested in Bitcoin (negative adoption, or disadoption of sorts). As you can see, the number of Bitcoin users doesn't necessarily tell us the real adoption rate, which is a bit counterintuitive, of course...

That's why I started this thread addressing that point exactly