It is hyperoptimization, because most people do not do a rigorous cost benefit analysis of all their behavior based on the marginal costs and utility of their time. Most people barely do
any kind of optimization, in fact. They might decide not to vote because they're cynical or lazy, but that's (strictly speaking) different from
rationally choosing not to vote because you consistently avoid doing things which are a net negative in value compared to your time.
I've already proven for you that a single vote matters. You can reject that proof, just like you can reject a proof that the square root of 2 is irrational, but you wouldn't be doing so on a logical basis. That covers the positive question of whether or not your individual vote matters - any argument against this basically boils down to, "But I don't feel like it matters, because so many other individual people are voting."
As for the normative case of whether or not to vote - again, I'm open to your time being so expensive you shouldn't vote in principle. But in practice, I'd be pretty skeptical of most people trying to make that claim. If Jeff Bezos and homeless people alike are willing to vote, a plea to the value of your time isn't that compelling, even in the ivory tower of game theory. If such a person spent (cumulatively) an hour or two without deriving any productivity from their time on election day, they should have voted if they were otherwise capable of doing so.