Donald Trump is incompetent but Nixon was insane. Nixon once tried to order a nuclear strike on North Korea while he was DRUNK!
In an entirely separate incident, Nixon, drunk a lot of the time in 1973, was passed out drunk during a critical moment when the USSR was about to intervene militarily to aid the Arabs in the Arab-Israeli war which could have triggered a full nuclear war.
He was doped up too. He was secretly getting 1000 tab bottles of the prescription anti-seizure medication Dilantin not from a doctor but from a buddy of his who “fixed him up”. Nixon said it helped him sleep. The problem with that is that Dilantin has SEVERE negative interactions with alcohol and is known to cause suicidal ideations in 1 in 500 people who take it, that is take it without alcohol and in regulated doses under a doctor’s care. Nixon was popping them like Skittles and washing them down with whiskey.
His secretary of defense took the step of getting all of the joint chiefs together and getting a pledge from them that they would not obey Nixon’s orders to launch nukes unless they were all in unanimous agreement.
Now that is a scary story of a truly insane president.