When to admit failure

I’m a firm believer in the saying ‘there’s no such thing as failure’. Failure is only an opportunity for growth and learning. However, I’m beginning to wonder about that. I have this neighbor who’s been working on this project for months. Basically he’s doing the proverbial square peg in a round hole thing. He’s got an old machine and is trying to put a new part designed for a different machine onto it. No matter what he does, it doesn’t work. He’s asked everyone in the neighborhood for ideas about how to make the 2 pieces fit together. Everyone says the same thing – get a new machine. He asked me to contact the manufactures of both the machine and the part since he doesn’t have internet access. I had a feeling they would say it wasn’t possible but I never turn down a request for help. While both replies said in no uncertain terms that what he was trying to do couldn’t be done, one said it was dangerous. It went on to add something to the effect of risking life-threatening injury because the machine could explode if he was even sort of successful marrying the 2. Uhm, yikes. However, this still didn’t give him even a moment of pause. Nope, he took one look at the emails I’d printed out for him and grunted. Then continued to tinker away. I’m not sure how long he’s planning to continue on this crazy path. Yet, it’s clear he’s not learning anything nor is he growing. Far from it – he seems to be getting more stuck in his ways and more stubborn by the day. Yesterday, he yelled at a neighbor who offered to buy him a new machine. Said he would make this work come heck or high water. Yeah, this is one person who has a firm belief in the saying ‘failure is not an option’. Is there something in your life you’ve done this with? You’re just so stuck on trying to make it work you don’t even see that giving it up would be so much better? Huh, I wonder if there’s anything I do this with…