The idea that suffering leads to ennoblement of the soul has historically been a major fixture of Christian thought, especially Russian Orthodox thought. Like many other ideas, it is testable empirically; and, if there is no time or resources for an empirical study, then gleaned from history.
Among history's great villains, Stalin and Genghis Khan had experienced serious suffering prior to having done what they did; Hitler had not. Among history's great political leaders, Mandela and many of the independence and civil rights leaders had experienced serious suffering; America's founders and most of its elected leaders hadn't. Among scientists, artists, inventors, thinkers and business leaders, we likewise see a very mixed bag, with some having undergone serious suffering and others not having undergone serious suffering. What we see, effectively, is people at all levels of personal goodness regardless of suffering undergone - a result we would see when there is no correlation one way or another.
From this I conclude that there is no correlation between suffering undergone and personal goodness, and that the idea that suffering leads to ennoblement of the soul is wrong.
The matter however does not end there. There are others who claim such things as that everyone creates their reality, or that suffering that people undergo are punishment for things done wrong in the past lifetime or in this lifetime or something that they manifest from within. According to that belief, people who suffer are worse than people who do not suffer - a belief that likewise is repudiated by an analysis that there is no correlation, one way or another, between suffering undergone and personal goodness.
A more sensible analysis is this: That people can take different things from experience and apply them in whatever manner they like. Someone who's been through a genocide can either decide that killing is wrong and work toward peace, or they can decide that the world is cruel and that they must be ruthless to survive. Someone who's been through a bad marriage can either be motivated to make things better for others in bad situations or to hate the opposite gender. Someone who's had bad experience growing up can either decide to make things better for others or to make others miserable. And so on down the line.
Does suffering lead to ennoblement of the soul? And obversely, is suffering a punishment for personal badness? I think that we can see from history that it is neither of the preceding, and that it is something instead that people can take into any direction they choose.