Keep in mind that those who qualified for CTY at younger age still need to re-qualified at 7th grade with SAT score. For that reason, some parents just wait until 7th grade to do the test and apply for CTY.
Having said that, I really don't see any downside besides the testing fee. People test for CTY for various reasons, summer camp, family program, online classes are all very good reasons. Advocacy is another one if you are thinking of grade skipping or acceleration. Sometimes, it is just curiosity of how advanced your gifted child is. Finding that out early on is actually important.
