there are some horses out there worse thousands of dollars.
Though it's already been said a few times, there is generally no money in the horse business. Even if horses are 'worth thousands of dollars', those sale prices are nothing compared to the cost that goes into maintaining them. To put in some numbers one horse costs roughly around $3,000 annually (more or less) just for ideal upkeep, and this would be for a healthy, easy-keeper and does not include any emergency vet calls, training fees, or things of that nature. Once again, that's an estimation for good mandatory upkeep - things like feed, bedding, deworming, trims, shoes, vet check-ups, vaccinations, dental work, board fees (if the horse isn't kept on your property), etc.
Considering the difference after a horse is sold, depending on how long the owner who's selling has had the horse (or depending on circumstances), the loss of profit could be - and usually is - huge. Very rarely would you ever come out with more money than you put in. Even if you had a really great horse that you had highly trained and were ready to sell for some decent bucks, you never know when 'luck' could turn around with horses. That 'star horse' could get terribly injured the next day and be rendered unsuitable for riding, making it worth nothing more than a companion horse, and if your income was dependent on that horse then there'd be a serious problem. There is no solid foundation on such a business; it's very chancy, and unfortunately the odds are against it.
Even if you do pursue education in horses, I agree with what others stated: have a back-up plan (a different career to 'fall back on', in other words), and don't go to college for it. I'd find going to college for horses, while sounding extremely fun, to be a bad idea, especially if you want to have a business in something like training or boarding. College is going to put you up to your neck in debt to begin with, and if you go into a non-profitable business while being in extreme debt, that'll turn into even more debt, and you then wouldn't be able to provide what is needed for your business.