Most GNU/Linux users have never heard of GNU. Like Ishamael, they say they
are "Linux users". They praise the features in the operating system, its
security, etc. And yet, as you write, "the free software movement remains
tiny even after the biggest spying scandal in history". If people still do
not care about their computer freedoms (such as "not being spied on"), it is
because they did not hear enough about freedoms. Not the opposite.
Once a user acknowledges she has fundamental freedoms that deserve to be
respected, she never goes back. A transition is certainly needed: she starts
with imperfect solution: free software on Windows, then a distribution with
blobs because she did not know about firmware issues, etc. Anyway, her
objective is to reach 100% freedom in her computing life. Not 99%. The FSF is
the much needed lighthouse guiding towards this objective.
If the user only heard of the practical advantages of some free software (she
has rather heard about "open source software"), she may use it. However, she
sees no problem in using proprietary software in parallel (why would there be
a problem when Linux includes proprietary firmware, when her distribution
proposes Adobe Flash during the install, etc.). And she goes back to
proprietary software whenever it becomes practically better. Insisting on
practical advantages only has a short term "influence". It is "pointless"
w.r.t. the goals of freeing computer users.
That is why "the free software movement remains tiny even after the biggest
spying scandal in history".