It is a strange question and still a good one, any ideas?

Video games probably exist cause 1 guy just thought one day 'Imagine a game, but on a screen'

then pong was made

No.

but why do they make them

I can think of a few reasons off the top of my head:

• Sometimes it's an indie dev trying to tell a story/pass on a message to the players.
• Sometimes it's a way of escapism through the means of a simulated life in another world.
• Sometimes it's a cash grab.
• ...and sometimes they just make it for the memes, or just because they can.