Reining is a lot of hard work. I tried saying this earlier. You need to have a talented horse in order to compete. A good trainer is really important because, surprisingly, riders don't necessarily have to be that good. When you get to NRHA shows, the trainer usually gets the horse ready and you just ride. Of course, there are those few horses and riders who make it on their own, but it's rare. I cannot emphasize this enough: it's expensive!!
Honestly, I'm amazed at how many people want to do reining, think they have a horse that will do reining, etc. Why not cutting? Probably because you need cows.