You don’t have to completely focus on one or the other - you can prioritize computer science while still practicing art on the side. The key is managing your time well and not burning yourself out. If you can handle programming every day and drawing some every day that’s great, but really if you can take the time to draw a little bit even once a week or once every other week that’s better than never drawing until you graduate. Use it as a way to handle the stress of university and give your mind a break, even.
MysteryMeat makes a good point in that you can use the money you make from your tech job to fund your game company endeavors. I’d also add that connections from your job or university can be valuable for trying to start a company. Just make sure all your agreements are clearly laid out on paper.
You may find that problem solving techniques you use in computer science are useful for learning art and vice versa. For example, debugging techniques can be used for figuring out weak points in your drawing skills. The more you learn, the more tools you’ll have at your disposal for problem solving and creating.
