The geocaches mystery

[comfortably_numb]

Until now I'm still asking myself about those damn caches and their purpose...
But first, some explanations, here are the meanings of the acronyms used in INFRA :

TFTC : Thanks For Those/That Cache(s)
TB OUT : Travel Bug OUT
BYOP : Bring Your Own Pen

So the geocaches are supposed to be hidden in some secret places for other people to find them. Find a cache is rewarded by an item (cheap) locked inside.

Here are my questions :
Who the hell put all these geocahes around?
Why are they all empty?
As they are all empty, who found them all before Mark?

[Fortigurn]

Yeah I was really hoping for some resolution to those at the end.

[oku]

I expected to see a whole pile of them in Mark's apartment.

(and just as a small side bar the travel bug out boxes are described on the net as a sort of survival kit in case of emergency or when you are traveling, containing water, medicine etc.)