Profitability might not be the issue, neither are supposed to function solely to make a profit. From the linked blog post, referencing an email, it is stated that its costing more than the revenue can support.

From a general internet search:

c(3)'s can’t engage too much (or at all) in legislative stuff but a c(6) can

c(3)'s are supposed to do things to help a group outside of itself while c(6)'s are supposed to exist to support their members

c(6)'s aren’t required to report personal information of a person/entity making a donation to the IRS or public