Perhaps their proximity to events and having the power to make history distort the perspective of world leaders.
Donald Trump is not known for the sobriety, consistency or even accuracy of his pronouncements, so the current US president might be particularly prone to hyperbole when it comes to judging the state of superpower relations.
His declaration this week that the US “may be at an all-time low in terms of relationship with Russia” was another example of his tendency to exaggerate, either through ignorance of his subject or an irresistible desire to dramatise.
The Cuban missile crisis of October 1962 is widely regarded as the most dangerous moment of the cold war, as Washington's threat of full-scale retaliation to Moscow's planned missile deployment in the Caribbean brought the US and Soviet Union to the brink of nuclear conflict.
Just a year earlier, following the construction of the Berlin Wall, a row over access for US diplomats to Soviet-controlled East Berlin prompted US and Soviet tanks to face off for several hours across Checkpoint Charlie.
Dangerous
At that time, the confrontation was seen as the most dangerous since the Berlin blockade of 1948, when Soviet forces prevented all traffic reaching US-, British- and French-controlled sectors of the divided city.
The US and Britain responded with a massive airlift to Berlin, which was deep inside Soviet-occupied eastern Germany. Soviet ruler Josef Stalin ended the blockade in 1949, rather than attack the planes and invite war with the West.
A year later the Korean war began, dividing the peninsula and pitting Soviet- and Chinese-backed northern forces against the US-supported south.
All these moments appear to have been far more dangerous than the current diplomatic deadlock between Washington and Moscow, especially given Mr Trump's repeated calls for a rapprochement with his Kremlin counterpart, Vladimir Putin.
Mr Trump is by no means the first superpower leader to seemingly overstate the perils of his time, however.
In 1986, then Soviet leader Mikhail Gorbachev reflected: "Never, perhaps, in the post-war decades was the situation in the world as explosive and hence, more difficult and unfavourable, as in the first half of the 1980s."
1983 was a particularly tense year, though at the time only a few people realised how close the world had come to calamity.
‘Evil empire’
President Ronald Reagan was massively strengthening the US military and had dubbed the Soviet Union the "evil empire". He was poised to deploy short- and mid-range nuclear missiles to Europe and had backed the nuclear defence initiative – known as "star wars" – to destroy incoming missiles and neutralise the Kremlin's strategic arsenal.
The air forces of both superpowers regularly probed each other's defences, and on September 1st, 1983, the Soviets shot down a Korean Air flight from New York to Seoul that strayed into Soviet airspace, killing all 269 people on board; the Kremlin claimed the Boeing 747 was on a spying mission for the CIA.
In the early hours of September 26th, 1983, alarms at an early-warning station near Moscow screamed that US missiles were heading for the Soviet Union; only the scepticism of duty officer Stanislav Petrov, who correctly suspected a technical fault in his base's systems, prevented a possible retaliatory strike.
Six weeks later, as the US and Nato partners staged massive war games in Europe, elements of the Soviet military went on high alert. A matching response from US forces could have sparked an escalation, but no such move was made, and so the world remained oblivious to how potential confrontation had been averted.
Anatoly Dobrynin, Soviet ambassador to the US from 1962-86, said that his bosses in Moscow had for decades placed considerable trust in the US system of checks and balances to prevent any surprise military attack.
But that calculation changed with Reagan.
‘Unpredictable’
“Reagan is unpredictable. You should expect anything from him,” Dobrynin recalled being told by Yuri Andropov, Soviet leader from 1982-4.
Andropov was head of the KGB when Putin joined the Soviet security service, and Russia’s current leader is known to be a great admirer of his former boss.
Putin may not have liked the policies of three US presidents he dealt with before Trump, but at least they were broadly consistent and predictable; Russia likes to be the maverick in world affairs, and expects Washington to play the "straight man" – a role that does not suit the new resident of the White House.
Russian foreign minister Sergei Lavrov complained this week about "the extremely ambiguous and sometimes contradictory ideas that have been expressed in Washington across the whole spectrum of bilateral and multilateral affairs."
How low a point we have now reached in US-Russia relations will only become clear in the months and years to come. But it seems that Putin, like his hero Andropov, must get used to living in an age of American uncertainty.
Flashpoints in US-Russia relations:
1948-9 – A Soviet blockade of Berlin prompts a massive airlift by the US and Britain to keep the city supplied.
1950-53 – The Korean war pits the Soviet- and Chinese-backed north against the US-backed south.
1961 – Soviet and US tanks confront each other across the Berlin Wall for several hours amid a row about diplomats’ movement around the divided city.
1962 – The US and Soviet Union come to the brink of nuclear conflict after the Kremlin moves to deploy missiles on Cuba.
1983 – A malfunction at a base near Moscow suggests the US has launched a missile attack against the Soviet Union. The duty officer suspects a fault and ignores the alert.
1999 – As peacekeeping forces deploy to Kosovo, Russian troops occupy Pristina airport ahead of Nato forces. US commander Wesley Clark demands a robust response, to which the British commander of the Nato peacekeeping forces, Mike Jackson, responds: "I'm not going to start the third world war for you."