Well, I don't know about you, but I haven't been particularly impressed by the results that an already dumb populace has achieved recently in America. So America getting even dumber doesn't particularly bode well...
We ought to be concerned about the numbers even if there's not much we can do about the kids entering adulthood.
Well it's not really numerically the same as voting for the candidate you hate the most, it's numerically the same as not voting. And to be honest, it really only matters if you're in a potential swing state. And I'm saying this as someone who still votes despite having lived in a deep red state where my presidential vote always doesn't matter (but I go anyway because down ballot votes do matter and I might as well vote the whole ballot).