Duct tape it up and use gurilla glue when it does snap? Thats what ild do although i dont have any experience

Maybe wrap some tape around it. Stop flexing your cans so hard (apologies if this advice isn't helpful because your head is huge)

I'm really sry if this doesn't belong here, I just saw the crack today and got really scared.

This was the only place I could ask

Get a thin long piece of wood/metal, tape it parallel directly on top of the headband on both sides of the crack. That should add some structural integrity

Hockey tape and maybe cut up an old credit card for a splint.

Get some carbon fiber or Fiberglass strips. Some epoxy. Lay out the epoxy and put the strip down. smooth it out. Let it cure. Sand and paint. Bedliner would work or flex seal.

Ugly way would involve a strip of metal and a rivet gun. You could use threaded rivets, so bolts could be used.

Aside from what everybody else is saying, make sure you extend the headband arms to an appropriate length for the size of your head. I've broken a few headphone bands precisely with the same crack location and appearance because I kept them compact while wearing them, which means the bands flex wider than they should to fit over my stupid dumb big head.

try to take better care, use a headphone stand also. about all you can do