Even people who are capable of enduring major tribulations and who proved themselves willing to actually offer up their lives are not always capable of bearing the suffering of small troubles.
There was once a Chabad Hasid who eventually apostatized, and toward the end of his life became the chief censor of Russia.
It is said about him that even forty years after he apostatized, though he had long since ceased to keep the mitzvot, he would mention the name of the Baal HaTanya (Rabbi Shneur Zalman of Liadi) only with the greatest awe and reverence.
This individual, once a pious man and a Torah scholar, was not broken by sudden, momentous tribulations but by smaller troubles.
To earn a living, he had to work in a large city, even though, as a Jew, this was prohibited by Russian law.
He was repeatedly caught and evicted until the strain of this lifestyle finally broke him.
–Rabbi Adin Steinsaltz
From Talks on the Parasha