Let us start by looking at a few groups that vote more and a few corresponding groups that vote less often. After identifying the groups, we can think about why they behave as they do.
First, whites tend to vote more than non-whites. African Americans have caught up to whites in recent elections, but Asians and Hispanics continue to vote much less often than whites (and blacks) do. Second, people with more education tend to vote more than people with less education. Third, older people vote much more than younger people. Finally, richer people tend to vote more than poorer people do. Let us think about why this might be.
One reason for some of these differences is that some groups have lower costs for voting. Political scientists believe that if the costs of voting are too high, people will not vote. Voting does not cost money, but it does have costs in terms of the time and effort needed to become educated on the issues and candidates and (in most states) in terms of the time needed to actually go and vote. We can say that better educated people will not need to take as much time learning about issues and candidates because they are likely to be better informed about the political system. The same is true for older people who generally have more time and are more likely to spend some of that time following politics.
Another reason for some of these differences is that some groups derive low benefits from voting. Political scientists believe that people will not vote if the benefits they get from voting are too low. The benefits of voting are psychological and emotional. People get an emotional benefit from voting if they feel that it is their civic duty to do so. They get benefits from voting if they feel that they are participating in a system that works for people like them. In general, white people and richer people are much more likely to feel that the system works for them. They are much more likely to feel that they have a civic duty to vote because they are more likely to feel a strong connection to the country and its system.
Thus, some groups vote more than others because they have lower costs for voting and/or because they derive more benefits from doing so.