To answer your question: Millions of Americans are also entitled to their opinion, just as you are. That is what free speech is. But people tend to give more weight to someone with the accomplishments, skill  and wisdom of  a Coach Popovich. Here are just a few of what his skill and wisdom have accomplished: Coach of the year in NBA THREE  times. FIVE  NBA championships. He was on  the coaching staff of several US men's Olympic and national  teams. He has the most wins in the NBA for any coach with a single team.  He is to be head coach of the next US Men's basketball team, Just to name a few. How many millions of Americans can make the same claims. Plus his "opinion" about Trump's lack of truthfulness is a verifiable fact. 
You self proclaim yourself a Ronin. But a Ronin is lordless and masterless, but it seems that have made Trump your lord and  master. You comes to his defense even in the face of facts that confirm his lying.  Does the  truth matter to you???