I see.
I expect most people not to change much at their core. When there is someone who I am not into now, I'll let it be. There are people who are in love with the potential idea of a person: "If only... then..." They'll date them, hoping they'd change, but it never happens. I am not like that. I do gauge how someone will develop in the future and whether I'd be on board with that or not – whether it would be an improvement to them as a person and our potential relationship. However, if I did not like them enough already as they are in this moment, I would not go for it. I find it rather detrimental to love someone only for what you think they should or could be.
Having said that, supposedly it can be very beneficial if people see the best in each other. To some extent, this is a positive illusion, but one that is not grounded on wanting to change someone or feeling like they'd only be good enough if they were different.
So yeah, I never attempt to change anyone. Most people won't change at their core, and their bad habits can only be changed when they want them to change. Once a guy who was interested in me figured out I wouldn't date someone who was addicted to smoking cigarettes or drinking, so he tried his best to limit his consumption of those things. I did not tell him to do that, he did that on his own accord. I knew it would not make much of a difference, that it wouldn't last, and I was not interested in him in that way anyway. I am rather sure he tried giving it all up mainly because of me; he tried to "change for me". Needless to say, it didn't work out. He eventually started drinking and smoking again, and that was that.
Personally, I am much more tempted to change myself to appease another person. But it is really exhausting. I cannot keep it up for too long. And on some level, it is psychologically painful. It is almost like selling your soul to the devil, hoping he'd love you for doing so. But at the end, your soul is gone and the devil values you even less than before because you entirely gave yourself up for him, lacking in self-worth and -respect.