This is something I have pondered many times through my life, for a while I was adamant that people could change because I had changed, there was a time In my life when I was a very different person with very different motives, I was a self centred ass for many years.
But, on deeper contemplation, the change that I made was more of a reversion to the way I was before I became that other version of me. So can people change? Certainly, but maybe only in a transitory kind of way.
Meangful, lasting change has to come from a deep internal recognition of the need to change, a place of sincere repentance. And old habits can come back too easily without daily commitment to the changes made. Humility before God certainly helped me 🙏🏼