[SatvikBeri]

Scared Straight is a well-known program that has been well-studied and found to cause significant harm. "In 2004 the Washington State Institute for Public Policy estimated that each dollar spent on Scared Straight programs incurred costs of $203.51."[0]

It was based on an intuitive idea: if teenagers see how bad jail is, they'll want to do anything they can to avoid it. That turned out pretty poorly - they instead built social connections with criminals, and were substantially more likely to get involved with crime themselves.

[0]: https://en.wikipedia.org/wiki/Scared_Straight!