For reference, the current estimated amount of desktop Linux users globally is somewhere between 60-80 million. In English-speaking countries, the total is around 19-20 million.

That sounds about right when comparing Microsoft's claim of "1 billion" Windows devices. 5% of a billion is 50 million(not a perfect comparison as 5% Linux is total including MacOS/others from statcounter but you get the idea). So 50 million to 100 million Linux users globally sounds about right.