"Cannot Make It" (CMI)

I remember when I was younger I would say "sorry, I cannot make it." This was an apology said in relation to an appointment or some meeting with a friend that I was unable to attend to.

These days if someone were to refer to someone else as a person that "cannot make it", they are saying something pertaining to their lack of perseverance or character. It is now meant as a derogatory term. It's totally colloquial and almost like a localised version of a slur.