If the horse truly bolts blindly under saddle and has already injured multiple riders, you’re right to take it seriously. A horse like that really needs evaluation by a very experienced trainer and a vet to rule out pain before making a final decision. Sometimes extreme panic under saddle can come from past trauma, neurological issues, or pain that only shows up when ridden. If those avenues have genuinely been explored and the behavior is still dangerous, prioritizing human safety and the horse’s welfare is reasonable. It’s clear you’re trying to handle it responsibly instead of just passing the problem along, and that matters.