I think the main things to understand are, first, that the SU was already mainly controlled by revisionists before Stalin even died, reducing Stalin to a borderline figurehead for revisionists to work under. Secondly, the Secret Speech included extensive deception in its accusations against Stalin and co., with a very long list of supposed crimes that were “not previously known” because they either didn’t happen at all or didn’t happen as Khrushchev depicted them, which contributed to making Stalin look monstrous and therefore make destalinization look appealing. Third, Khrushchev purged high-profile supporters of Stalin, most notably Beria, which really made it less viable and less appealing to oppose destalinization. Lastly he kind of did get pressured out of office eventually, not because of destalinization but for the adjacent reason that he just kind of didn’t know what he was doing, which is only to be expected from someone like him.