What Motivates Political Violence?

One of the conventional political theory explanations of political violence is that it is a response to the apparent futility of using the political process.

But, experience seems to be telling us another story.

For the last two years, Republicans have controlled the Presidency, both houses of Congress, and the U.S. Supreme Court, as well as many state governments in "red" states. They have as much political power as they have ever had in the United States.

Republicans also controlled the Presidency and both houses of Congress fro the first six years of George W. Bush's eight year Presidency (from January 2001 to January 2007), but the filibuster in the U.S. Senate was still meaningful then and the Republicans didn't have a filibuster-proof majority in any of those years. The U.S. Supreme Court was moderately conservative in those six years, but not nearly so conservative as it is now, following Gorsuch's and Kavanaugh's appointments to the U.S. Supreme Court. So, Republicans really have more power under Trump now, than they did then.

Prior to George W. Bush, the last time that Republicans controlled the Presidency and both houses of Congress, however, was in March of 1933 during the Presidency of Herbert Hoover, at a time when the Republican party was a very different, pre-realignment party.

Yet, politically motivated violence and threats of violence remain overwhelmingly right wing political tactics in the United States.

What explains this observation? Why is the right wing continuing to resort to violence and violent threats when it has all of the political power through electoral means? Is political violence just a lagging indicator?

Historically, terrorism has not been exclusively right wing, but has been right wing much more often than it has been left wing.