For many, despising Trump has nothing to do with politics

Investigating reports of criminal activity is what law enforcement was created to do.  When Trump and his gulls claim that the special counsel's investigation is a witch hunt,  they are trying to dismiss Trump's lifetime of nefarious activity.  His record is something he built himself over the decades, not something manufactured by the opposing party.

In an editorial, The New York Times summed up his life history:  

Mr. Trump has spent his career in the company of developers and celebrities, and also of grifters, cons, sharks, goons and crooks. He cuts corners, he lies, he cheats, he brags about it, and for the most part, he’s gotten away with it, protected by threats of litigation, hush money and his own bravado.

I recall a long conversation with a retired commercial banker from Chicago in the late 1980s in which he explained why Chicago businesses leaders wanted Trump to stay out of their town because every where he went he gave business a bad name.

Two months before the 2016 election,  the Huffington Post published a story with the headline

Trump’s Criminal History Should Be Front and Center.

In March of that year, the conservative National Review, published a story with the headline

The Definitive Roundup of Trump’s Scandals and Business Failures

These stories did not mention Trump's politics.  They focused on his belligerent dishonesty, and they cited the documented incidents in which he put it on display.

Trump's charges that the Department of Justice and the FBI are engaged in a witch hunt must be assessed in the context of his history.  Any person with the record of malfeasance such as Trump's is someone law enforcement is obligated to monitor and investigate, because he is, to use the catch phrase, "a person of interest."  His record of past and  continuing misdeeds makes him a perennial suspect.  Law enforcement keeps  lists of known offenders so that they know where to look when certain crimes are committed.  Trump appears prominently on such lists.  The investigation into Russian interference with the 2016 election will examine his relationships with Russian oligarchs and organized crime figures.  His ties to them make him a person of investigative interest.  The Department of Justice would be grossly neglecting its duty if it didn't investigate Trump.  So, Trump tries to discredit the DOJ and the FBI because they are examining the facts of Trump's business history.

While the news media reports and svpeculates about Trump's latest tweet and the political
turmoil he creates,  business journalists who have covered Trump over the years don't let Trump's misdirections of attention divert their eyes from his continuous history of malfeasance and mendacity.  The truth of what Trump is has been established by his own behavior.  Those who know his history are convinced it will be revealed with a huge load of documented facts.  That is why Robert Mueller, the FBI, and law enforcement agencies throughout the nation are so dangerous to him.  They will expose him.