The Wiki article on ibogaine suggests that risk of permanent brain damage and fatal heart arrhythmias are one of the factors that has slowed research in the US, though research does still continue. Plus I suspect that a drug to break addictions that has hallucinatory side effects might not be looked upon kindly by some hardcore anti-drug people.
Another problem is that to do the kind of research needed to get US FDA approval, you need lots of funding to support years of well-controlled clinical trials. That money has to come from somewhere. In most medication studies, the company with a patent on the drug pays for it. That’s not applicable here. You’d need government money (NIH, often) or a private institution to grant money to study it. So I bet if you could convince some billionaire to give out millions in grant money for a research team to work on the project, it might have a chance.
This is true for any potential medication or medical device, really. Individual investigators who develop something need to raise cash to do testing, and often get investors in the project. If something that isn’t foreseeably patentable - and/or has a host of other potential concerns - is being worked on, then it’s so much more difficult to deal with.
I can’t remember (or find) the name of it for the life of me, but there’s a documentary on Netflix Instant about an addict that goes through ibogaine treatment. If you’re interested in the subject, it’s pretty good. Maybe someone else has seen it…