Every person has an element of self interest that motivates them in their daily lives and actions, and that is perfectly normal.
However, when people only consider their self interest in the sacred act of voting on leadership of their nation or their state, that is something to be deplored as improper behavior.
So what motivates so many people in how they vote, in no special order?
Their biases and prejudices toward people different than them
Their desire to control other people’s lives
Their religious beliefs which they wish to promote on others
Their lack of concern over poor, boorish behavior by some candidates
Their sense of patriotism and nationalism
Their ignorance about public issues and viewpoints of candidates
Their personal egos, connected to insecurities
Their lack of compassion and empathy for others
What distinguishes progressives from conservatives is that these nine factors do not play into their voting patterns!