Good question.
It reminds me of a ted talk by the founder of social bite in Scotland. She gave a story of a homeless man who she gave a job to a roof over his head. It took dozens of issues with stealing, not turning up for work etc etc before he started to settle and come “good”.
Sometimes people deserve a 5th, 6th, 7th, 9th chance. Sometimes they don’t.
Regardless, don’t ever become hardened by the exploitation of your kindness! 😀