Why you should fear Donald Trump

Mark Macias has offered up his advice to 2016 candidates such as Hillary Clinton, Marco Rubio and Jeb Bush on CNBC.com as if they were his clients. But in this piece on Donald Trump, Macias's advice is actually for the rest of us — he says Trump would be a nightmare client who wouldn't follow his advice anyway!

In business, you fear the person who has nothing to lose and everything to gain because he will fight you till the end. In politics, you fear the person who has everything to lose and nothing to gain, especially if he has totalitarian control.

Donald Trump
Brendan McDermid | Reuters
Donald Trump

These general principals are why NBC and every GOP presidential candidate should be very fearful right now of Donald Trump. He won't play by the rules in politics because he has run a totalitarian regime. He will also fight till the end because he wrongfully believes he has nothing to lose in business.

Read MoreOp-ed: Trump turns GOP race into reality-TV circus

The proof for that analysis is already underway. Less than 24 hours after NBC severed its business ties, Trump began throwing dirty bombs at the network. As a former producer and executive producer with NBC in New York, I can tell you Trump knew exactly where to hit.

Trump also knows what sells on TV — and, as a publicist, he understands how to frame it in a controversial way that grabs headlines. That's how his reality-TV program, "The Apprentice," became a sensation in season one. We love hearing what uncensored people say when the camera is rolling. We love even more the reaction it ignites in the prey.

But politics are supposed to be civil. Presidential politics are supposed to be diplomatic especially since the person who steps into the Oval Office has the power to end life in the U.S. and abroad.

This is why it is so disturbing as a publicist and political strategist when I hear a presidential candidate speak in sound bites without concern for the consequences. It is dangerous in government when there is no substance behind the words. But that's what Trump did for his opening act as presidential candidate.

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"When Mexico sends its people, they're not sending their best," Trump said. "They're sending people that have a lot of problems, and they're bringing those problems with us. They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people."

As a Mexican-American, words can't describe how offensive that "sound bite" was. Trump's speech wasn't political or divisive. It was pure racism, playing to the lowest common denominator — fear. I heard this venom in Arizona (where I was born) with local Sheriff Joe Arpaio but you don't expect to hear it from a presidential candidate who is supposed to unite the country.

The Republican Party already has an image problem with Hispanics, which both parties know will influence this election. The immigration question will inevitably come up in the GOP debates and if Trump speaks like he's on "The Apprentice," the Republican Party will be in damage control before the debate is even over.

Read MoreMexico to Trump: You are one 'ignorant,' 'prejudiced' hombre

But that's just a preview of what's to come if Trump gets a seat at the first presidential debate. He is going to spray the same venom at every candidate on stage because he knows his "sound bites" generate headlines. Expect Trump to use verbose phrases in that debate, involving themes like, "you're fired," "Iran is a total disaster," "this administration is a total disaster," "America is a total disaster," and the all-encompassing, "it's a total disaster," which can apply to any situation.

Republicans should be in crisis control right now.

In PR, you never want to work with clients who don't take your media advice because you are always in crisis mode. Everyone who reads the newspaper has seen the politician apologize because he went off message. It happens in local town elections — all the way up to the presidential elections. The only difference is how they spin it. Local politicians usually apologize while national communications teams usually say the candidate didn't fully understand the question.

You can't give media or political advice to Trump because he will undermine you every time. He believes he is smarter than everyone, so why should he listen to someone who doesn't understand?

In 2010, I ran the media campaign for an unknown politician running for the U.S. Congress. I predicted privately to friends that he didn't have to worry about any opponents beating him. He was perfect for that district, articulate, smart, good-looking and a veteran but after I got to know him personally, I knew it was only a matter of time before he self-destructed. He is no longer serving in Congress.

Donald Trump won't self-destruct but he will lose this presidential campaign and very likely blame others. Hopefully, when that time of reflection arrives, he will become a more sensitive and humble man.

Commentary by Mark Macias, head of Macias PR, a global public-relations firm, that has run media and branding campaigns for politicians, tech start-ups, financial firms, nonprofits and companies. He's also author of the book, "Beat the Press: Your Guide to Managing the Media." Follow him on Twitter @markmacias.

Disclosure: NBC and CNBC are both divisions of NBC Universal, which is owned by Comcast.