Users generally update by default, if thousands upon thousands didn't it's because someone else fucked up.
I find it funny how a small group of people thinks they know better than the outer community, to the point that they feel like they should have a say in what thousands of businesses use to run successful code.
More than this, I would argue that most people using Python 3 are those new to the language. This is only from personal experience, so it's really just anecdote.
PS: In a kind of jesty side-note, I know the general argument is that "python 2 was broken", but really, how broken can something be when thousands of businesses depend on it and more than that, choose to keep using it when a "better" alternative comes about?