Why wait until the strap fails to chuck it away?
The op is way ahead of the game.
Your partially quoting seems to me to be driven by some strange urge to prove the OP is at fault in some way. What you partially quoted was:
Either way I don’t see why lack of knowledge of materials science should render someone an idiot or anything strange in chucking away a cheap £15 helmet because the strap failed… even if it just worked loose it’s a £15 helmet… if the strap keeps slipping I’ll just write it off.
I’ll just chuck it and move on…. my more expensive Bell 3R … that’s annoying… I should really put some effort into getting it fixed or replaced…I’m simply not going to put that effort into a £15 quid helmet though…