People don’t vote because they think that their vote doesn’t matter. How can one person make much of a difference? they ask themselves, ignoring the history that shows that one vote has made a difference thousands of times.
Why do people vote? Some are angry, inspired, strategic, or enthralled. There is also duty:
Some people vote because it is their constitutional duty to vote, and they take their constitutional duty very seriously. There isn’t that much required of an American citizen, especially since the draft went away. You have to sign up for Social Security and Medicare. You have to pay taxes. You have to serve on a jury every once in a while (provided that you aren’t a convict). You aren’t compelled to serve the country in any other way other than to show up to vote, and you aren’t even required to do that.