How is “a change for the better” used?

In Joker (2019), one line is: “And until those kind of people change for the better,”

Which movie is “a change for the better” from?

The clip at the top of this page is from Joker (2019).

a person, thing, situation, etc. that is better / worse than the previous or present one

Heard in 1 movies

Oxford100% of films
a person, thing, situation, etc. that is better / worse than the previous or present one
And until those kind of people change for the better,

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

And until those kind of people change for the better,

Said in 8 films · #1