system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If glass is an insulator, how come when you touch a Plasma Ball, the beam inside goes to your finger/hand?

When a Plasma Ball is on, the beams go all over the place, but when you touch it, it knows your hand is there and they concentrate onto your hand or finger.

How is this possible?
gpt
Insulator is a relative term. Electricity will travel the easiest way it can and in this case, it's easier to go through the glass, through your hand, to ground than it is to travel through the air. 

Glass is not as conductive as things like metals so we'll call it an insulator, but that's just relative.