Make your decision based on the quality of the program, mentorship, and imprimatur. You're most likely going to pivot around anyway at some point in your life.

Make your decision based on the quality of the program, mentorship, and imprimatur. You're most likely going to pivot around anyway at some point in your life. 25K isn't really very much money, but if you can get paid to have an awesome learning experience, deeply engaged guidance, and a significantly increased chance of getting some angel funding after the program, that seems like a pretty good deal and might be worth being flexible on your idea. On the other hand, if you're super-passionate about your idea and really know it's what you want to do, you should stick to your guns. The accelerator may be impressed enough to let you in anyway, but you should obviously be ready to go it alone.