i'm personally a pretty competitive person, so i would join a ranked jam, even without prizes, just to have the satisfaction of trying to be the number 1 (not as it ever happened tho).
The sad of starting a new jam tho is that as no one knows you, your jam probably won't have more than 3 submissions (if it end up having submissions at all btw). A couple of people will join your jam, but only a few will submit on it... sad