I'm always intrigued by the ways in which the human wetware can go dramatically haywire. At this point the investigators are saying they don't know the motive for the Nashville bombing, but that may be a category error. Here's what I mean.
The action was meticulously planned, carried out to perfection, and constituted elaborate theater that clearly appeared designed to send a message. The perpetrator evidently wanted to minimize human casualties, although he was willing to accept a substantial risk that there would be some. But he also wanted to cause immense property damage. He played the iconic song Downtown, performed by Petula Clark, in between warnings of imminent explosion. That looks like a commentary of some sort on the entertainment district where the attack took place, but on the other hand the nearest target, that took the most damage, was an AT&T facility and the most severe impact of the attack was disruption of telephone and Internet service. But he left no manifesto and apparently made no attempt to provide an explanation for his actions.
So maybe he thought that 5G cell service is the cause of Covid-19. Maybe he thought people are spending too much time with their devices which is psychologically or socially unhealthy. Maybe he objected to the debauchery of night clubs, or more specifically maybe the real target was the nearby Hooters and he objected to the commodification of the female body. Who knows? But whatever the intended message, who was it for and what were they supposed to do about it?
The point I want to take from all this is that even when investigators do define a "motive" for acts such as this, they're really missing the point. Timothy McVeigh, who you will recall destroyed a federal building in Oklahoma City killing dozens of civil servants and children in day care, didn't bother to issue a manifesto or an explanation. However, once he was captured he told investigators he was angry about the federal siege of the Branch Davidian compound in Waco, Texas, and the subsequent fire and loss of life. But does that really constitute a "motive"? The Social Security and Department of Agriculture clerks and administrators and their children who he killed obviously had nothing to do with it. With whom was he trying to communicate by this action and again, what were they supposed to do about whatever it was he meant to say?
The same can be said for the vast majority of terrorist actions. In the case of the Las Vegas massacre this is obvious -- it was as unintelligible as the Nashville bombing. But even in the Pulse nightclub shooter, the guy who shot up the synagogue in Pittsburgh, many others, in which there is hatred or resentment of some arbitrary group of people -- gay people, Jews -- just going out and killing a bunch of them at random has no evident point. It doesn't advance the perpetrator's agenda in any way. These people are really talking only to themselves, it is something in themselves they mean to kill. Sometimes they do kill themselves, of course, but not always. The Las Vegas gunman apparently did not originally intend to die, he had plotted his escape; but in the middle of his rampage he turned the gun on himself. McVeigh must have expected to be captured and he embraced execution. That was likely always part of his plan.
When we use the word motive we mean that a person has an objective -- some outcome they wish for -- and undertakes an action in order to bring that about. I don't think that applies in most of these cases. But it might sometimes. Osama bin Laden and his co-conspirators wanted to draw the U.S. into a conflict with Islamic countries that they believed would be damaging to U.S. standing in the world and provide a boost for recruitment into their brand of Islam. It worked perfectly. But that's a whole different phenomenon.