Love this thread. As a returning adult rider (been back in the saddle for 3 years now), I'd also say that it's wise to think seriously about leasing instead of owning. This might be specific to urban folks like me, but:
If I owned a horse--my dream since childhood--I would be spending all of the money I currently use to take lessons on the horse's board and vet care. I wouldn't have had lessons every week for three years on different horses, which definitely helped me regain my skills on buckers and bolters and green horses. I leased an OTTB mare for most of those three years: she was my equine soulmate, but if I'd owned her I would have been in an impossible situation last summer when we had to move across the country at the exact same time that she developed a career-ending stifle injury. I helped find her a new home, but it would have been devastating if I'd owned her because I wouldn't have had the funds to move her and cover her medical fees, let alone the ability to pay for her board when she wasn't able to be ridden at all.
I'm rambling, but point being: there are lots of perks to leasing if you find the right owner and the right trainer. I'm at a small dressage barn now with wonderful people, starting a lease and still able to pay for lessons from a very good trainer--and there's no guilt about only being able to drive out from the city a couple of times a week, because the horse's owner rides him on my off days. Owning is great, but don't think that you can't be a horse person if you don't have your own steed. :)