I didn't attend TC, but the quote from your friend asserting that people who reject the program are essentially losers is irrational, illogical, and moronic. What he is essentially positing is that the ONLY valid perspective is a positive one. It proves the point that dissent or critical thinking is undervalued.
I did not go to a program for drug use or delinquency. Many of my peers also did not. And yet, there we were. Whether someone split, left, or graduated is inconsequential to the fact that the program practiced systemic, trenchant, and pervasive verbal and psychological abuse. If a kid were a drug addict, bipolar, or simply rebellious would not convince me that their stay at the program was therapeutic. In fact, the opposite. I don't feel this way because of rules or work details. That sh*t is petty and frankly, inconsequential to the fact that the program practiced systemic, trenchant, and pervasive verbal and psychological abuse.
It is very tiresome to continue to explain to Program People that dissenters are not rule whiners. Do you think we would be talking about this over decades later if we simply hated a few rules? No. In fact, I could give a rip what happened to me a long ass time ago. I don't want today's kids to be placed in programs that practice, yes, again, systemic, trenchant, and pervasive verbal and psychological abuse.
I don't know much about Teen Challenge pro or con. However, it is true --based on my experience, research, and professional and academic expertise-- that I lean toward skepticism. Nice brochures and "Jesus Saves" slogans are not effective arbiters of therapeutic ethics.