So we all know that the main reason the Watchtower Corporation prohibits holidays, extra-curricular sports, higher education, etc. is that this money could potentially become "voluntary donations" with just a little guilting and manipulation. In the minds of the Brooklyn brass, money that isn't spent on all this worldly stuff is potential liquid revenue (at least some of it anyway).
Now let's go extremely conservative for a minute and say that the average "worldly" person only spends a total of $300 a year on Christmas, birthdays, St. Valentines, Father's Day, Mother's Day, extracurricular school sports, higher education, and all the other stuff that the WT frowns upon.... We all know that the real number is much higher than $300. But assuming that's the number, if you multiply that by 7 Million Dubs, that's a total of $2.1 Billion dollars a year in potential revenue for the WT.
With contributions dwindling and rag revenues declining rapidly, I'm sure the old farts in Brooklyn are hard at work right now searching for something else to prohibit... I'm guessing wedding anniversary parties will be next on their "prohibited spending" list. Just a few proof texts taken out of context should do the trick... cha-ching!