Majority of the time, they aren’t the ones riding or training. They simply buy expensive horses they are told will be successful & find professional trainers/riders for them. Whether it be for fun or as a form of advertisement, it’s actually very common, especially at high levels (Grand Prix, olympics, the Triple Crown) seeing as these horses can be incredibly expensive to purchase and take care of. It does come with some merit, as they can potentially have an easier time finding riders for their horses, as they’re potentially famous (or just rich) :^)
Definately not. Unless the person knows how to take care, excercise, train and properly do equine things then I am sure it won't. That is another reason why even if you are an equestrian, if you don't havr much experience, and are a beginner should not lease let alone buy a horse.