I didn't mean to imply you sounded ungrateful or whiny, because you don't. Just tried to give you some justification for why your folks feel the way they do.
My parents have never understood the horse thing, and for many years thought it was just a phase. 33 years after buying my first horse, I'm pretty sure it's not just a phase!
They never did 'get it', and even all these years later my mother will still ask me, 'So, when are you going to get tired of those horses and start living a normal life?' Um, when they pry the reins out of my cold, dead hands?
Boy does this hit home! My dad loved horses, used to train them back when dinosaurs walked the earth......but mom-even after all these years-up until she was too senile to know my name, actually, she was STILL asking me the same thing....along with "are you still married to.....HIM?"
And, DH has actually asked when I might stop riding, and my answer was the same as yours.
That said-I was fortunate enough to have horses growing up, BUT, mom made life miserable and complained the whole time. So, which is worse-not sure. Finally I can happily afford to have them without anyone questioning.
They are a privilege, not a right. That is true at any age, no matter who is paying the bills.