I had an arabian for 11 years, at my farm. I loved a lot of it - the biggest trouble I had was company. For awhile I lived with my mom and she had a horse too, so we could spend time together with the horses and go out riding together. It was really nice, we groomed them and wandered around the farm riding the fields for fun. We generally just rode around our own place, casually and sponanteous usually. After several years she was no longer able to ride, had sold her horse, and I bought my own farm. I had a lot less fun with my horse after that. It gets lonely to just ride on your own, but trailering to get to others is much more of an affair.
If the horse will be at your house and you are the only horse person there I'd consider how you feel about being alone all the time while with the horse. If your family isn't into horses, how often a week will you able/wanting to spend time with your horse rather than with your family? If you would keep the horse at your place, but trailer to events, maybe ask to go along on a trail ride with someone so you can experience transporting horses and all that. Some people love this, but its a very different experience. There are many ways to do "riding", some work better for different situations and people than others.
If more than you in your household likes horses then 1 won't be enough, which needs consideration.
Like all animals, owning horses can be done expensively or more manageably. We had enough land to do our own hay, which helped a ton, and didn't do shows, which made it much cheaper. I also didn't get "into" the fancy tack or clothes. You can easily drop thousands of dollars on those. BUT, you don't have to. You and your horse will have a perfectly delightful time with much cheaper/second hand tack and you can ride just fine in pretty normal clothes. You can make your own nice rope halters. Our vet even taught us to do our own shots, so we didn't pay for that. Expenses of course occur, but you can do it in a less expensive way if you wish.
One thing I did early on that was highly beneficial for me was to go to natural horsemanship seminars or to get/watch materials around this. A number of the programs are set to teach you as much as the horse. A learned a lot about good (and safe) ground manners to teach a horse, and learned how to teach it to my horse.
ALWAYS wear a helmet, I suggest anytime you are on a horse, even for short stints, and on the ground if around a horse you haven't known for a good year. I watched a helmet save a life in front of my eyes. Don't underrate them.
