“Now available from Hasbro™, the Demon Core Playset! For the first time, now you too can experience the thrill of needlessly edging the most destructive force ever devised by humankind to the brink of supercriticality using nothing more than your own hands and a flathead screwdriver! (For… reasons!) Perfect for proving exactly who has the biggest balls in the room! Right up until you fry them off and give everyone in the vicinity Super Mega Turbo Cancer, of course! (Well, the lucky ones who manage to survive, at any rate 😁)”
Fr tho, these people were well-educated physicists with access to some of the most cutting-edge technology/equipment available at the time, who knew they were fucking around with what is probably the most powerful destructive force humanity has ever encountered/created in our known history… Less than a kilogram of the material in the bomb dropped on Hiroshima actually achieved fission, and yet that was clearly still more than powerful enough to cause death and destruction on a scale previously unimaginable - particularly for a single weapon.
And these guys then have the bright idea to basically flip a salad bowl over on top of it and manually try to maintain an aperture (with the help of a flathead screwdriver tip - for safety reasons, obviously) that is as small as possible in order to see just how close they can get it to the point of no return, ya know, just for funsies? Because humans are notoriously good at never making any sort of mistakes, right?
I can only assume this was their last resort after the excitement of auto-erotic asphyxiation via popping the hatch of the command module open while in orbit wore off.