There's always an onramp to applications for new forms of science and new techniques in math...and eventually, they find their way into practice, solving problems for millions of people. 

I did my masters' thesis on a very esoteric problem years ago, and it's now being picked up by applied researchers in robotics and machine vision.  I am getting monthly hits to the work. 

Slow adoption doesn't mean worthless work, at least in science.

There was a time 7-8 years ago when Hadoop was probably seen by some engineers as a waste of time.