No one:

The fact the he saw this probably means that he wakes up in the morning and examines his diamond play button

Rick put his hair there for safe keeping

"Whose hair is inside my KSI diamond play button?"

Jack: "there's a bit o' hair stuck in me playbutton"

Next up: there is a bubble in my glass of water

Jack: finds a hair in his diamond play button

He is actually wearing gloves to touch his diamond play button that is covered in smudges

In the letter they said “We’re actually scratching our heads” so they probably scratched their heads over the play button

Rick put his hair in every diamond play button, thats why he's bald

When your looking at the owner of YouTube’s hair

When I got this notification I thought I was reading the dictionary

"But Rick doesn't have any blummin hair"

Jack, I've been looking at the picture of the hair for awhile and I think I've figured it out. While Rick might not have any hair, he does have eyelashes, and it just to happens that hair is the size of an eyelash. I bet under the diamond, you'll find Rick's eyelash. Also, it could be literally anyone else that works there eyelash or very short price of hair.

It's Rick Astley's hair, you got rickrolled

if theres an air space in their why not get a can of compressed air and blow it out? also good luck with the world record :)

This will have more subs than Jacksucksatgeography soon lol

Is Jack wearing gloves so he doesn’t get finger marks on it so he doesn’t have to polish it?