Is the purpose of enlightenment, in the end, to sell books?

No. Enlightenment means to become aware of something/everything.
“Enlighten – ...To shed the light of truth and knowledge upon; to free from ignorance, error, etc.; inform. ...To supply with spiritual light, to give insight to.” -from Webster’s New Collegiate Dictionary, 1960 ed.

But that doesn’t mean that it couldn’t help sell books…

Not sure what you mean by enlightenment.

What you say applies to self-help books pretending to offer fulfillment of one sort or another. The quick fixes they propose do not help. The only ones who benefit are the authors.

There is no purpose to enlightenment except enlightenment.

There is an old Zen quote:

Before enlightenment, chop wood, carry water.
After enlightenment, chop wood, carry water.

@RedDeerGuy1 , I think I am seeing your point. Why bother studying philosophy, religion or the arts? Just a fricking waste of time. Doesn’t put any food on the table. Trump was perfectly right to slash the NEA budget. Bunch of parasites. This reminds me of something. What could it be? Oh yeah, this guy

I think you state it backwards. In the end, what’s the purpose of buying books?

We must advise you that any further attempt to suggest or imply any mercenary purpose in the study of enlightenment will see the matter referred to the courts.
Brian Spicer
Department of Legal Affairs
University of Trump

If the meaning of life reduces to a steak sandwich, bottle of Coke and YouTube videos then I could see how one might take a dim view of those who believe otherwise.