Do not quit school and do not give up on the horses. Learning to balance them will be a good experience for you. I am a PhD student, so very busy, and I manage to ride about 3x per week. I have 2 horses. I had been getting up early to ride, but since it is dark in the morning now, I have put my riding horse at a boarding facility so that I have access to a lighted arena, so I ride early or late. You CAN go to school and get to ride, but it's about compromise. I don't go out drinking so I can get up early, and I don't do much other than ride and go to school, but I manage. I don't buy anything other than ramen noodles and horse stuff either, or so it seems. I also know that I can no longer ride young, hot horses with the amount of time I have, and kept that in mind when looking for a new horse. I took up a new and difficult discipline on a quiet horse so that I wasn't bored, but also not in a lot of danger from not riding a youngster enough.
It may be more difficult in college, but again, it can be done. I managed to lease and board a horse even though I only made $900/month (although partly because I used a university facility. Full care paddock board is only $150/month for students). I also took riding classes through the university before I found the lease horse. If it's important to you, you can find a way to do both. Good luck!
Tug on anything at all and you'll find it connected to everything else in the universe.~John Muir