Why? It's probably one of the most popular editors for PHP/HTML/CSS/Javascript/Ruby/Python.
According to https://sublime.wbond.net/stats there are roughly 2.5M sublime text users. If even 10% of them paid for it, that would be 250,000. Assuming 10% is a little high, let's do 1% would would be 25,000.
Even if those numbers are wrong (which they may be I have no idea how he gets those numbers, and if everyone is using Package Control) there can very easily be hundreds of thousands of paid licenses.