First off, welcome to the forum
Good for you for having such a passion for horses, no one can break that or take that away from you. People can be funny sometimes how people think and behave. It can be harsh to not have that parental interest, I know I went through that growing up as well.
What you do have on you side tho, and it speaks louder than words is your parents love. They do care about your interest in that they have provided you with lessons and a way to spend time with what you love most. That to me, shows that they do care about you and what you love, your passion. I am sure they both work hard to be able to afford spending money on something that you enjoy so much(regardless of what you think you are good at or not).
Not everyone has the same interest, and it does sound a little cold they wouldnt try to even make some conversation about it BUT they do sound like parents who absolutely love you and work hard to be able to offer you what you love most, horses.