How Big is Kindle Unlimited? Is it 3 Million Subscribers? Is it 10 Million Subscribers?

Warning: This is not scientific. This is A GUESS. This is based on Assumptions and it's literally called a Guesstimate i.e. Guess + Estimate. Except for Amazon, no one knows exactly how many Kindle Unlimited subscribers there are First, let's look at various guesses over the years Fortune in 2015 thought Kindle Unlimited had 2 million subscribers The Passive Voice in 2017 thought Kindle Unlimited...