My experience is the opposite. Most of the staunch Mercurial supporters came from CVS or SVN and found Mercurial to fit better into their preexisting mental model of source control.
Users that started with Git are more likely to internalize Git's concepts as "the natural way to do version control", and more likely to find Mercurial counterintuitive.
Users that started with Git are more likely to internalize Git's concepts as "the natural way to do version control", and more likely to find Mercurial counterintuitive.