Yes they can change but it might not always be their own 100% choice to do so. I don't want to change, because I don't see a reason to, I'm getting closer to death by the day and I can't wait, this year will be the year, I can feel it, the culmination of the past 5 years, I've waited for any sign of "goodness" but we're only going into deeper amounts of shit, the last thing on my mind is what others think about my morality meter. Nobody cares, they all pretend to , this is just a sham shit show of a game where the players bullshit eachother into playing it so they don't have to alt+f4 together.
No matter how "good" I would become, no matter how well I would fair against life, no matter how much I would repress my emotions and be an obedient cogwheel nothing will change my baseline morality: not religion, not philosophers, not my parents, not my peers, no drugs, no activity, nothing will change the way I am because that would mean I would lie to myself and I hate liars the most.