APS Membership Discount

Makes perfect sense to me, as long as the 25% incentive results in at least 25% more buyers due to that incentive. Anything less than 25% new buyers is a loss, and anything more is a gain.

I guess the long term effect could be that buyers now know that an incentive will be offered in the last quarter and will hold back their purchases until that quarter, resulting in a net loss overall. It's kind of like watching my spouse wait until that one special day at Kohl's when the prices dramatically drop, you get double coupons, and lots of other incentives. Any other day we shop there, she says, "Nobody pays those normal prices. They always wait until the sale days."

Exactly this.

To be fair, that isn't the entire picture, as those additional 50 memberships aren't pure profit. There is a cost associated with those 50 memberships: the 50 copies of The American Philatelist and their associated printing and (likely the biggest component) the mailing costs.

I agree with your general premise, but it's not pure gain.