Stripped T30 Bed Screw

That's normal. Those bolts suck and this happens to everyone lol

 

sharp chisel on outside of bolt head, hitting CCW, done it many times..

 

I tend to pull out a hammer before a drill:

Impact screw driver, hammer in best fitting bit first. Remember to preload in the loosen direction. Can also try a Shake N Break driver for air hammer.

The old slot for a screw driver doesn't tend to work on bigger bolts. But it can be adapted with a strip of steel and vice grips - grip side of metal strip in the slot, apply torque, hit top of steel strip with hammer repeatedly.

Use that cut slot and a chisel to hammer the edge counterclockwise. Air hammer with flat chisel even better, about 45 degree downward so it digs into the steel.

Hammer in dimple on the edge with pointed chisel, can also drill a dimple. Then punch/chisel in dimple and hammer counterclockwise. Air hammer with pointed chisel even better, again 45 degree downward.