I feel hay and grass may end up more expensive than anon thinks... For grass, you need a big place where your horse can graze. Anon either is such a big landowner or intends to rent such land, but it won't be cheap. Then the hay for when the horse is kept indoors... Gotta be a lot of hay. And the means of bringing and storing the hay may be of non-negligible price. Then there are vet bills, because horses can get sick or injured...

I knew someone who owned horses long ago. Well, more like someone whose parents owned horses since we were kids. They even had a coach that these horses could pull. But they didn't use it as a means of transportation unless just doing a simple roundtrip for leisure, and there's a simple reason for that: You can't leave your horse for hours on a parking spot. You can tie it up somewhere maybe, but not for a long time, there aren't many places fit for leaving horses nowadays.