A movie might be based on real events, but the director doesn’t have to treat it what happened as gospel. A good example would be Tony Scott’s Domino, based on the real life Domino Harvey. The story is completely fictional (if you can follow it) but the filmmakers weren’t interested in telling a straight bio pic, opting instead to express her balls out personality through a fantastical tale. They didn’t get the truth of what happened, but rather the truth of her. And, for me, this is of most importance.
Now, a filmmaker doesn’t have to treat a person’s story as the final word, but a level of respect for the subjects involved doesn’t hurt. Unfortunately for the real life people behind Pain & Gain, Michael Bay is their storyteller.