1. For one thing, a U.S. president would be the first one to tell anyone that he no longer has any personal life anyway. I imagine almost every form of communication he has is under electronic surveillance for any number of reasons.
2. When I read these reports of this FBI investigation in 2017, I go back and remember the part of Comey's testimony in June 2017 when he described a conversation with Trump from January of that year ... in which Trump told him he might ORDER Comey to have the FBI investigate him -- to vindicate him. It was Comey who told Trump that this would not be a good idea.
During that meeting: “The FBI was telling the president-elect that the allegations were salacious and unverified, yet at that very moment they were presenting them to a federal court as information the judges could rely on to authorize spying.” https://www.foxnews.com/opinion/andrew-mccarthy-fbi-russia-investigation-was-always-about-trump