A lot of those guests are likely search engines, vulnerability scanners, and other bots. I just checked apache logs on a few sites I have access to and found that about 85% of the page hits were easily-identifiable bots, not even counting the malicious ones which don't have an obvious signature. The web is a pretty noisy and hostile place.
And as already mentioned, many guest hits are regular users who weren't logged in at the time. For example, I default to a not-logged-in lightweight browser for most viewing, only using a full-featured browser for posting. And when viewing from a phone, requests often go through an accelerator cloud service which makes a single person appear to be dozens or hundreds of different IP addresses.
So, in general, I'd remove a digit (or two) from the number of guests to get a closer estimate of the actual value.