The reason Trump is convinced that the multiple tax cases and DOJ investigations against him are nothing more than political hit jobs and witch hunts designed to make him look bad, is because that's what he himself did while in office.

"While in office, President Donald J. Trump repeatedly told John F. Kelly, his second White House chief of staff, that he wanted a number of his perceived political enemies to be investigated by the Internal Revenue Service...
...
Mr. Kelly said that along with Mr. Comey and Mr. McCabe, Mr. Trump discussed using the I.R.S. and the Justice Department to investigate the former C.I.A. director John O. Brennan; Hillary Clinton; Jeff Bezos, the founder of Amazon and the owner of The Washington Post, whose coverage often angered Mr. Trump; Peter Strzok, the lead F.B.I. agent on the Russia investigation; and Lisa Page, an F.B.I. official who exchanged text messages with Mr. Strzok that were critical of Mr. Trump."

I guess Shakespeare was right. The lady doth protest too much, indeed.