Still Worth to be on Amazon’s KDP Select?

Recently an author wrote in a forum: “I’m seriously debating whether or not I should opt out of the KDP Select program (after my three months are up). I’ve had very few borrows to make it pay, so it’s only really the promotion days that seem to be a plus. My last book did okay on free promo, but not a lot of sales to follow.” Well, I have read similar posts during the last two or three years on a regular basis.

.
Many authors doubt, as Amazon Kindle Free Days, CountDown Deals and Borrows are...