The problem with being a rising star in a dictatorship where the only rules are the whims of one individual is that you tend to attract a lot of attention. This, of course, could put a target on your back. If you outlive the dictator, the purges, and the possible wars, however, it could be you occupying the big chair when the dust settles. Nowhere is this more clear than in the life of Nikita Khrushchev.
Before rising to the top of the Soviet Union's oligarchy, Khrushchev started his Communist career as a political commissar during the Russian Civil War, was then sent to Ukraine to carry out Stalin's purges, and somehow survived World War II's Eastern Front, where Communist Commissars were specifically targeted by the Third Reich. After the war, he spent much of his time very close to Stalin...and survived.
He even told the USSR that Stalin was stupid and his policies sucked. Not in those words, but that was the gist.
Khrushchev implemented many of Stalin's policies without question, and did as he was told throughout his ascendancy. He also didn't make any move against his boss while he was alive. Instead, Khrushchev waited until after the death of Stalin to denounce the "Man of Steel," along with his domestic policies, his personality cult, and probably his mustache. But while Stalin was alive, Khrushchev was the best salesman for global Communism Stalin could have had.
During his time as the leader of the Soviet Union, he met with everyone who would have him, including famed anti-Communist Richard Nixon. He even managed to avoid a nuclear war with the U.S. President Kennedy. He didn't need the bravado the Red Army wanted him to show during the Cuban Missile Crisis – Khrushchev already showed his by surviving every deadly situation thrown at Russia.
If you can survive Stalingrad, you can survive anything.
Khrushchev survived Stalin because he'd proved his mettle many times over. Khrushchev was the epitome of the Soviet worker class. He was from a poor family of peasants, he went on strike against the Tsarist government as a metal worker in World War I, and he chose the right brand of Communism when the time came. When given a choice between the Bolsheviks and the Mensheviks, he chose the group who prioritized winning over everything else. He was so loyal to Communist ideals that he refused to allow his wife a religious funeral after she died. That's dedication.
He immediately joined every Communist government program and school he could, using connections to get into everything, like a good oligarch. When it came time for Stalin to purge, Khrushchev was in a trusted position. To maintain that trust, Khrushchev was willing to send his closest friends and coworkers to the gulag and the executioner.
In case you were wondering, he killed a lot of people. Like, a lot.
So to survive the dictator's whimsy, you have to prove you aren't out to topple the dictator. The best way to do that is help kill the dictator's enemies... before someone else accuses you of being the dictator's enemy. The second best way is not to make waves. When Khrushchev appealed to Stalin to help fight the famine in Ukraine, Stalin thought Khrushchev was getting weak and sent him an overseer from Moscow. Khrushchev promptly became "ill" and all but disappeared for two years.
Not annoying Stalin about starving people probably saved his life and career. In Stalin's last days, Khrushchev was called to be near Stalin and in the dictator's inner circle. Here, the future Soviet leader survived many long nights of drinking and dancing at Stalin's command, coining the saying: "When Stalin says dance, a wise man dances."
Krushchev learned to take a nap in the afternoon so he wouldn't fall asleep in front of his boss.
These guys killed several hundred thousand people, maybe more. That's not even counting the famines.
After Stalin died, his inner circle vied for power and fought amongst one another publicly. Not Khrushchev – he was demoted and accepted his situation. He soon found the others had fought themselves out of a job while "humble" Khrushchev was elevated to the title of First Secretary of the Communist Party. By not overstepping his bounds as his rivals did, Khrushchev became the least objectionable choice. It didn't hurt that he was generally very good at whatever his job was.
He was so good even after he was ousted from power, Khrushchev managed to avoid being murdered by enemies like most powerful people in dictatorships so often are. He retired to a dacha in the countryside and died of a heart attack.