Happiness ain't a thing in itself -it's only a contrast with something that ain't pleasant. And so, as soon as the novelty is over and the force of the contrast dulled, it ain't happiness any longer, and you have to get something fresh.
Every civilization carries the seeds of its own destruction, and the same cycle shows in them all. The Republic is born, flourishes, decays into plutocracy, and is captured by the shoemaker whom the mercenaries and millionaires make into a king. The people invent their oppressors, and the oppressors serve the function for which they are invented.
We don't cut up when mad men are bred by the old legitimate regular stock religions, but we can't allow wildcat religions to indulge in such disastrous experiments.