And this assumes that your vote gets counted.
On the other hand, democracies tend to be better to live in than non-democracies, and I use the very simple metric of which countries have immigration problems versus which countries have emigration problems.
Using a similar approach that people have a fairly good idea of how to attain their ends, it's obvious that groups which want to retain a grasp on power don't like voting. They don't have it at all, or they make it totally corrupt, or they terrorize voters. That last is actually kind of surprising when it's so easy to fake results. Tentative theory: aside from the practical effects of voting, even moderately honest elections are the government showing respect to citizens, and citizens showing respect to each other.
So you might as well vote.