Am I crazy for wanting to try to get my friend get out of their relationship?
Maybe, why does your friend want to get out of their relationship?
The person they're dating is using them and treating them poorly.
Tell your friend your opinion about this person and that you feel that they're not treating them well. Make your case and hopefully your friend will listen to your advice.
I hope so, but they may not want to listen to me because I had a past relationship with the person they're dating.
All you can do is tell them what you know and how you feel. Since you have personal experience with the person they're dating, your friend may be willing to listen to you. At least if you try, you'll feel better about the situation instead of saying nothing.