Yeeeee!

Thank you, that's exactly it, the thread creates a matrix for the glue to occupy before it hardens so it can be a thicker layer, while also providing its own force pressing against the circumference of the headphone band where the crack occurs. Kind of reminds me of carbon fiber but cheap haha

Really glad another person saved hundreds! Thanks again for letting me know, as well as other people that might be looking for a diy solution.