Fitness instructors are people, some can easily be like that - why not? There are people who suck at their job in every field. But given the heroin ending, hopefully this is fake.
This is why I wish I had a fortune teller to say exactly when I am going to die. If you knew you were going to go out on a certain date, you could abuse opiates for months before your body gets used to them and then avoid the eventual darkness of deep addiction.
Someone, who ridicules people for some characteristic while they are in the process of improving that characteristic, has understood so little about life.