The No Kings Protests coincide with Trump's sad military parade. An estimated 5 million people (according to organizers) showed up and protested. G. Elliot Morris estimates 2.6 million attendees, representing 1.2 - 1.8% of the U.S. population.
Moreover, these weren't just progressive liberals or left wing people of the Coastal Elite variety showing up. Even in crimson red states saw people showing up. Look at Boise Idaho! The important thing is to recognize the extent to which Trump's public support has deteriorated.
Why does public support matter? It matters in so far how much resistance Trump sees. In a world where, like he imagines, people are non-playable characters (NPC), without agency, free will and opinions. This is a view of a sociopath, but this world view expects no resistance for only from a few pesky left wingers. This is not the world we live in. People are responding in horror and are outraged by plain cruelty of Trump's Gestapo, kidnapping people off the streets, courthouse, and schools.
Protests matter in proportion to an unpopular weak president. Even Putin, a man who has rigged every election and thrown every popular dissenter off the balcony of a hotel, needs public support. There is a reason why the use of the military is the last thing an autocrat does. They require a public that is not terribly too resistant to their policies and would-be popular leaders stay silent. It's why places like China crack skulls early on before protest reach critical mass or develop a charismatic popular leader. By the time you need the military to suppress protests, its often too late.
Strength as autocrat requires shutting down dissent, like from a popular young charismatic leader saying you're bad, wrong, and dumb. You as a autocrat look weak and have no ability to control the populace or sway popular opinion. One could argue, Trump sending the National Guard and Marines to LA was a sign of weakness and Governor Newsom looked strong standing up to a pretend king. In WWE parlance, an organic popular leader draws heat from the public. They are energized in a way that saps strength from the Heel.
Much of the power of tyrants comes from people anticipating what is expected of them and doing so before they are targeted. Mass protests demonstrate people dissenting at scale, despite the fear they may have of being singled-out themselves.
For now, Trump and his ghoul, Stephen Miller, are doubling down on state kidnappings and workplace site raids. They believe they can get away with it and not have people notice. Jamelle Bouie gets at their fundamental miscalculation:
Here we see Trump’s fundamental problem. He and his White House seem to think that the cost of their policies — the fallout from their effort to mold the country to fit their nativist and mercantilist obsessions — are indirect. Who cares about a few thousand protesters in Los Angeles, or even a few million undocumented immigrants, out of the more than 340 million people in the United States? But the reality is that to harden the border and more tightly police immigration — to remove as many unauthorized people as possible — is to necessarily subject American citizens to the scrutiny and violence of the state. External control requires internal suppression
...
Both Trump and Stephen Miller, the chief architect of the administration’s immigration policies, may have imagined that their crackdown would isolate a relatively small group of people and be met with indifference by most Americans, giving Trump and Miller free rein to do as they pleased.
No doubt they will continue to dig in their position and continue to cry out for public to join them in their cruelty. If these massive protests are any indication, its a matter of time when normal conservatives who don't like radical rapid change join in these protests in large numbers.