So You Think You Bought the Wrong Horse?
A lot of time, these horses make the best horses for young riders' first mounts. They also fit in well often at lesson barns and summer camps. Maybe even therapeutic riding.
If you need to rehome your horse for the reason of soundness, advertise and network with locals and the online horse community. Be honest, be willing to show all your horses vet records if necessary, or for the potential new owner to get a second opinion. Check the college programs as well; they do need beginner horses too sometimes, depending on their program at the time
Consider a Horse Rescue
If your horse is not sound enough to ride, and you have exhausted all options and can't afford to keep him, you can look into horse rescues. Often though, as with dog rescues, horses that are in safe homes are not a high priority for rescues since they work with limited resources.
Euthanasia: Dangerous Horses or Unsound Horses
If your horse is dangerous for you or others to ride or even be around on the ground, euthanasia is an option. There is no shame in it, and there is no horse on earth that is worth getting hurt over. There are some horses in this world that we are just not meant to be riding horses or even pet horses—just like in people, dogs, cats, any living thing really. Some minds just aren't right, and no matter how hard we try, we will not be able to connect with them.
Euthanizing these types of horses not only keeps anyone else from being hurt, but it also saves the horse from being passed around from place to place and inevitably falling into the hands of someone who might not treat them well. You will know you did everything you could and were responsible for keeping other people and your horse safe from harm or mistreatment. It is not the wrong choice after you have exhausted every avenue to put your horse at peace.
If your horse is so unsound that it is inhibiting his quality of life, it is probably kinder to euthanize than to rehome him to a strange place, but that is an individual decision that everyone has to evaluate the factors and then decide. A horse not sound enough to ride at all, has little to no value, just being a pet or companion horse, and just like the ill-tempered horse, this puts them in danger of falling into the wrong hands.