I'm not finding horses to be any more expensive than motorcycles. About $50 a week on average I easily spent that on motorcycle riding. I figured motorcycles cost of operation to be about $0.50 per mile on average over a year. It's easy to put 20,000 miles on one in a year.
Horses, have minds of their own and require more personal investment, in time and effort. And at horse events there are no sons of anarchy tough guys. No "biker" bull ******. And the police aren't out to prove something to the guy on a horse, as they seem to be about the guys on motorcycles.