Based on your priorities it might not be such a bad idea to continue with school. My mom graduated nursing school at 58 just because she was bored and wanted to do something different. She could have continued to be a med tech and sailed into retirement, but she decided that going back to school paying for it out-of-pocket and loosing 2 years worth of earnings was worth it. Granted my dad still worked and their house was almost paid off with a decent size in retirement accounts.
It seems like you will be finishing undergrad no matter what so I'll comment about grad school. I would recommend really asking yourself why you want to do graduate studies? Is it for the prestige, the piece of paper or the just pursuit of knowledge? If it's just for personal knowledge then do it as cost effective as you can, meaning you might now even need to enroll in a program just do self study.
Another alternative is to get your employer to pay for it, you'll know if your studies will actually be work-related. You said you wanted to get into sport science, which if related to statistics is along the lines of calculating shooting percentages, batting averages, team statistics. I'm afraid that you would need PhD level credentials to develop those systems, but you don't need a PhD to help implement them. Basically let the brianiacs work on the math and you can work on the data input, management, and presentation.
You should have a very concrete plan on how your post grad studies will help you get into the career you want. Not some general idea, I mean like talking to people in the industry and getting their advice specific information.
Good luck.