It depends on a lot of factors. How big the horse industry is in your area, what working student opportunities there are for you, what your current course of study is, how much it's actually benefitting you (some are definitely better than others!), and so much more.
Additionally, both choices could be beneficial for you. Each choice may present you with different opportunities down the road. It depends on what you feel would be best for you, really. Take some time to consider the things I mentioned above and that should help you. Good luck!
I would stay in collage and have something to fall back on in case being an equestrain doesn't work out for you