Unsupportive Parents

My parents are never satisfied with the career I want. I really want to be a horse trainer but they try to discourage me from it even though they have no experience in the industry. My definition of a horse trainer and there's is completely different. They think I want to be the type that works for a rich person and trains one of their horses for shows. While that would be an amazing oppurtunity I know that's not realistic for me. I was thinking more of having my own barn and having clients and working with rescues. And when I mentioned that they said "oh well people volunteer their time with rescues and don't get paid" like they're not understanding that it can be a career also. They don't even know the correct names of the gaits of the horse. And my dad always critiques my riding when he can't even do what I do. They keep forcing me to be a vet or a marine biologist. Like the other night my dad says to me "goodnight my future veterinarian" When will they understand I don't want to be that! I can't handle blood (which horses have a lot of), I'd freak out during surgery and most importantly I can't trust myself with the life of someone's beloved pet. When will they see me for who I am?