Whether you want to admit it or not, some people commit themselves to these centers and come out straight / believing they're straight/cisgendered/etc. Their motivations are generally because they come from a culture/family that is not accepting of who they really are. They themselves probably hate who they truly are. So they pay thousands of dollars for the chance of tricking themselves into believing that things are different.

Does it commonly fail? Of course.

But does there exist someone in the world who is living a happier life because they attended this therapy? I believe it's possible. And for that reason, I think banning it is wrong.

I imagine that choosing between being accepted by your community/family and being unhindered in expressing your sexuality is a very difficult and personal decision. I don't think any lawmaker has the right to make it for you.