On Thursday night, violent protests broke out outside Donald Trump's rally in San Jose, California. Trump supporters reported being beaten up by protesters. Some supporters had bottles or eggs thrown at them, were chased, or were spit on. Photos show a group of protesters shaking a supporter's car.

This is not the first time this has happened. Trump's rallies in California have been marked by disruptive and sometimes violent protests. For the first several months of Trump's campaign, protesters inside his rallies were often in physical danger and sometimes assaulted by Trump supporters; in California, the dynamic has been reversed, with protesters outside Trump rallies often the ones threatening and intimidating supporters.

Both of these dynamics are bad and dangerous. They are not going to get better.

Donald Trump rallies have become a locus for insecurity

Protesters and supporters have been facing off at Donald Trump rallies for as long as he's been running for president. The first recorded act of violence at a Trump rally depends on what you define as violence: If you count hair pulling or sign grabbing, it happened in the summer of 2015; if you draw the line at punching or kicking, it happened in November 2015.

Donald Trump has talked about it. Initially, he encouraged violence against protesters; he's since taken a winking, you-know-what-I-really-mean tone in discouraging it.

As tension around Trump rallies has shifted outside the arenas, and protesters have become more numerous and more aggressive, some of the people protesting are simply provocateurs. Others are longtime, hardcore "direct action" activists like the anarchist Black Bloc.

Who is your candidate? "There is no candidate" Who are you? "Anarchists" - @Jacobnbc describes protesters — Katy Tur (@KatyTurNBC) June 3, 2016

These are the sorts of people who turn up whenever they see an opportunity to disrupt the status quo. They were in Baltimore in 2015 and Ferguson in 2014.

But that doesn't make their presence inevitable. They aren't turning up to Bernie Sanders or Hillary Clinton rallies. Donald Trump's campaign has become a locus for confrontation and instability, and that attracts the sort of people who see violence as an acceptable way to get things done.

Trump poses an existential threat to many people

Before the political media was focused on the violence outside the San Jose rally on Thursday, they were focused on Donald Trump openly saying that the federal judge hearing class-action cases against Trump University should be disqualified because of his "Mexican heritage." Trump openly impugned the patriotism of Judge Gonzalo Curiel and millions of other people who are born to immigrant parents or belong to ethnic pride organizations.

This is not a small thing.

When his supporters have been the ones dispensing violence, Trump has often made excuses or ambiguously signaled support.

This is not a small thing either.

A lot of political commentators recognize that Donald Trump poses a categorical threat to established norms of American democracy, governance, and society. They believe that he represents (whether intentionally or not) an ideology that is hostile to groups of nonwhite Americans.

In other words, they believe there are Americans to whom Trump poses an existential threat.

You don't have to agree with protesters beating up Trump supporters, or even sympathize with them, to understand this. There are people who feel Trump's rise puts their lives in danger. And many people make decisions about what actions are "appropriate" differently when they feel personally under threat.

Violence and confrontation might be the only opposition to Trump some people see

When I talked to anti-Trump protesters earlier this spring, I heard a lot of variations on this sentiment from organizer Marisa Franco: "Trump has received an extraordinary amount of coverage by the media. So far he's just been able to roll out and say what he pleases, and people who like it go to his rallies and everyone else is just kind of watching."

As a journalist who's spent a lot of time fact-checking and criticizing Donald Trump, I was pretty frustrated by that sentiment at first. But most people who hear things Donald Trump says aren't necessarily reading Vox.com or other print and online outlets that have been covering Trump critically.

Much of the mass media (specifically television) really does cover Donald Trump without interruption, and doesn't pay much attention to peaceful anti-Trump protesting.

Only when protests get tense, confrontational, or violent do the cameras start rolling. And often the press has talked about protests as if they are violent when they haven't been — Donald Trump's canceled rally in Chicago in March, for example, was covered as if protesters were posing a threat.

So if you're a young person who reacts viscerally to the things Donald Trump says about Mexicans or Muslims, what do you see as the available, appropriate response? Furthermore, if you're a young person who personally feels the effects of Trumpist attitudes — if you feel that your life is under threat because you're nonwhite, and you don't feel that anyone appears to care — what do you think needs to be done?

And if violent protests at Trump rallies continue to escalate, and continue to get coverage, what sort of people are likely to show up to the next one?