Does it ever end well, I would ask?

My father owned a small business and at one time had three stores in shopping malls. He hired his nephew to work in one to mentor him and teach him the family business. The nephew stole cash from the cash register. It broke my father's heart. My dad's side of the family decided to stop m speaking to my father. The nephew went on to get arrested for something else on his own. That whole side of the family stopped speaking to my father and his family, for the rest of our lives, including at my grandfather's funeral.

My parents also hired my mother's brother to work on renovations on their house when he was an unemployed engineer. Decades later my uncle became very wealthy and successful and was a jerk to my parents, really forgot how they helped him out for over a year when he had no job and no money.

This happened to my cousin. He invested in a company that was to be run by his other cousin's husband (not my side of the family). It was a food production business and it failed miserably - lost everything. The guy who was running it was in over his head, no real business sense, but my cousin should have vetted the opportunity better (i.e. not giving them a dime.) Things are very tense now, they don't see each other on holidays, etc. The Aunts are also at odds because their children have had this experience with each other and they're taking sides. No one asked my opinion, so I've stayed out of it. A real shame.

How did it come about? What did you do about it? Do you know what made them that way?