JMU is betting on getting to the FCS championship game every year
When they do, it is worth it to stay in FCS. When they don't it isn't, they have less exposure.
The CAA tv deal is with Flo sports, basically pay per view. It is almost no deal at all. That plus, occassional single station, single market deals. When JMU decided to stay in FCS, the CAA had a national deal with NBC Sports. They lost that due to lack to viewers. The CAA is not an attractive sports property.
The Coastal vs Liberty bowl game this year was huge. They were both ranked. It got way more attention that the FCS championship.