It seems plausible to me. Think of the average citizen in this country. If you are 18-20 years old, you are probably excited to vote in a presidential election but as you go into your twenties, that excitement wears off and you become less likely to vote while you focus on college, starting a career and family. As you mature and settle into adulthood, you become more likely to vote because you are more informed than when you were in your twenties. By the time you hit retirement, your interest in voting begins to wear because getting to the polls isn’t as easy as when you were younger and you realize you don’t have much time left, so what is the point of voting for people who will have very little impact on your remaining years. ( I have a friend whose elderly father has sat out the last couple of elections for exactly these reasons)