I always vote regardless. Besides, there are elections other than presidential elections.
And even in a presidential election, there is psychological impact to the popular vote, even if a person, such as myself, is voting against the sure winner of my state.
Sad to say, the last time I voted for the winner in the state I was living in at the time was 1984, when I lived in New York and voted for Ronald Reagan. In 1988, I voted for George Bush, and while he carried Connecticut, where I live now, I lived in New York at the time.
Since then, the state I have lived in has always been carried by the Democratic presidential candidate, none of whom I have voted for.
But I still do pretty well at voting for the national winner.